全文获取类型
收费全文 | 2189篇 |
免费 | 144篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 24篇 |
妇产科学 | 24篇 |
基础医学 | 358篇 |
口腔科学 | 34篇 |
临床医学 | 178篇 |
内科学 | 586篇 |
皮肤病学 | 77篇 |
神经病学 | 215篇 |
特种医学 | 73篇 |
外科学 | 330篇 |
综合类 | 10篇 |
预防医学 | 69篇 |
眼科学 | 113篇 |
药学 | 92篇 |
肿瘤学 | 143篇 |
出版年
2023年 | 9篇 |
2022年 | 31篇 |
2021年 | 59篇 |
2020年 | 43篇 |
2019年 | 49篇 |
2018年 | 59篇 |
2017年 | 39篇 |
2016年 | 40篇 |
2015年 | 57篇 |
2014年 | 76篇 |
2013年 | 107篇 |
2012年 | 145篇 |
2011年 | 163篇 |
2010年 | 83篇 |
2009年 | 78篇 |
2008年 | 153篇 |
2007年 | 125篇 |
2006年 | 137篇 |
2005年 | 134篇 |
2004年 | 112篇 |
2003年 | 115篇 |
2002年 | 115篇 |
2001年 | 29篇 |
2000年 | 32篇 |
1999年 | 27篇 |
1998年 | 14篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 15篇 |
1991年 | 14篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1985年 | 6篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1932年 | 6篇 |
1930年 | 5篇 |
1929年 | 9篇 |
1928年 | 5篇 |
1924年 | 11篇 |
1923年 | 6篇 |
1922年 | 6篇 |
排序方式: 共有2353条查询结果,搜索用时 31 毫秒
111.
Verhagen PC Tilanus MG de Weger RA van Moorselaar RJ van den Tweel JG Boon TA 《European urology》2002,41(4):363-371
Prostate cancer is the most prevalent malignancy in males in the Western world and the second leading cause of male cancer death. Prostate specific antigen (PSA) based screening and case finding leads to identification of early stage prostate cancer. It is often difficult to discriminate between patients that need curative treatment and those that can be managed conservatively. Prognostic factors are used to make this clinical decision.Based on the classification proposed by the American College of Pathologists and the World Health Organisation, selected prognostic factors in prostate cancer are described. Clinical applicable factors are stage, grade and serum PSA. Prognostic factors that are not routinely used (for various reasons) are ploidy, histological type and cancer volume in needle biopsies. All other factors (including circulating tumour cells, angiogenesis, growth factors, proliferation rate, apoptosis, nuclear morphometry, neuroendocrine differentiation, loss of chromosomal regions, tumour suppresser genes and adhesion molecules) are promising as prognostic factor although currently their use in clinical decisions is not recommended. The role of these factors in prostate cancer growth and their predictive value are discussed.The rapid developments in molecular techniques allow assessment of structure or function of thousands of genes in a prostate biopsy sample. We expect that molecular characterisation of tumour material will become a clinically important tool to predict prognosis in patients with localised prostate cancer. 相似文献
112.
CD154 is expressed during treatment with calcineurin inhibitors after organ transplantation 总被引:3,自引:0,他引:3
van Rijen MM Kuijf ML Metselaar HJ Tilanus HW Bouma GJ de Weger RA Jonker M Kwekkeboom J 《Transplantation》2002,73(10):1666-1672
BACKGROUND: CD154 (CD40 ligand) monoclonal antibody prevents allograft rejection in rodents and monkeys. Inasmuch as calcineurin inhibitors (CI) inhibit CD154 expression by pharmacologic agents in vitro, we investigated whether CD154 is also inhibited by CI in vivo and in vitro during allogeneic stimulation. METHODS: CD154 expression was determined by immunohistochemistry and flow cytometry in human lymph nodes and spleen sections from rhesus monkeys with or without CI treatment. The effect of CI on induction of CD154 expression was studied by stimulating lymphocytes with phorbol 12-myristate 13-acetate (PMA) and ionomycin or with allogeneic monocyte-derived mature dendritic cells. RESULTS: Lymph nodes from patients with or without CI cyclosporine (CsA) or FK506 (FK) treatment showed comparable CD154 expression, which was present on the cell surface of T cells. CD154-expressing cells were also present in spleens from monkeys treated with CsA in comparable numbers to those in the nontreated group. Moreover, in several liver transplant rejection biopsies taken during CI therapy CD154-expressing cells were observed. In vitro, CsA and FK strongly inhibited induction of CD154 expression on peripheral blood mononuclear cells by pharmacologic stimuli. Maximum inhibition was found at 50 ng/ml CsA and 20 ng/ml FK. CD154 expression induced by dendritic cells in peripheral blood mononuclear cells or spleen cells was also almost completely inhibited by CsA. CONCLUSION: Although CI strongly suppressed pharmacologic and allogeneic induction of CD154 expression on T cells in vitro at concentrations at approximately clinical trough levels, CD154 is prominently expressed during CI therapy in lymphoid tissue and (sporadically) in liver allografts. This suggests that the CD154-CD40 pathway remains functional during CI therapy, which may contribute to allograft rejections in the clinical setting. 相似文献
113.
We report the composition of constituent fatty acids and molecular species of adipose tissue triacylglycerols of male weaned Wistar rats fed diets containing, in addition to 20 g corn oil/kg feed, 120 g per kg feed canola-type rapeseed oil, olive oil or conventional sunflower oil for 10 wk. The composition of fatty acids and molecular species of the triacylglycerols of subcutaneous, epididymal and perirenal adipose tissues did not differ among groups (P > 0.01), broadly reflecting the corresponding compositions of the dietary oils. The major molecular species of dietary triacylglycerols, especially trioleoylglycerol (OOO) and linoleoyl-dioleoylglycerols (LOO) in the rapeseed oil and olive oil diets, dioleoyl-palmitoylglycerols (OOP) in the olive oil diet, dilinoleoyl-oleoylglycerols (LLO) in the rapeseed oil and sunflower oil diets, and dilinoleoyl-palmitoylglycerols (LLP), linoleoyl-oleoyl-palmitoylglycerols (LOP) as well as trilinoleoylglycerol (LLL) in the sunflower oil diet were also prominent constituents of the corresponding adipose tissue triacylglycerols. On the other hand, predominant molecular species containing alpha-linolenoyl (Ln) moieties, e.g., alpha-linolenoyl-linoleoyl-oleoylglycerols (LnLO) and alpha -linolenoyl-dioleoylglycerols (LnOO) from the rapeseed oil diet were not prominent constituents of rat adipose tissue triacylglycerols, whereas LOP from rapeseed oil and olive oil diets and OOP from rapeseed oil and sunflower oil diets were distinctly enriched in the corresponding adipose tissues. Most of the minor molecular species of the dietary triacylglycerols from all the three diets were distinctly present in the corresponding adipose tissues. Thus, despite numerous biochemical processes involved in the metabolism of dietary triacylglycerols, a substantial proportion of the molecular species of adipose tissue triacylglycerols containing linoleoyl (L), oleoyl (O) and palmitoyl (P) moieties resemble those of dietary triacylglycerols. 相似文献
114.
Temporal and regional expression of NMDA receptor subunit NR3A in the mammalian brain 总被引:4,自引:0,他引:4
Wong HK Liu XB Matos MF Chan SF Pérez-Otaño I Boysen M Cui J Nakanishi N Trimmer JS Jones EG Lipton SA Sucher NJ 《The Journal of comparative neurology》2002,450(4):303-317
NR3A is a developmentally regulated N-methyl-D-aspartate receptor (NMDAR) subunit that was previously known as NMDAR-L or chi-1. Unlike other NMDAR subunits, NR3A inhibits the NMDAR-associated ion channel in a novel manner, and a role in synaptogenesis has been suggested for this subunit. Here, we report a comprehensive study to delineate the temporal and anatomic expression of NR3A protein in the mammalian brain by using a monoclonal anti-NR3A antibody. NR3A protein was found to peak at postnatal day (P) 8, and to decrease gradually from P12 to adulthood in the rat central nervous system. Moreover, NR3A protein was heavily expressed in all areas of the isocortex, portions of the amygdaloid nuclei, and selective cell layers and nuclei of the hippocampus, thalamus, hypothalamus, brainstem, and spinal cord. NR3A protein was also expressed in the cerebellar cortex, whereas only weak signal was detected in the previous in situ studies by using riboprobes. At an ultrastructural level, NR3A was associated specifically with asymmetrical synapses and localized to postsynaptic membranes. This information will facilitate future research on NMDARs by providing clues to possible inclusion of the NR3A subunit in NMDARs in many brain regions. 相似文献
115.
Plesnila N Putz C Rinecker M Wiezorrek J Schleinkofer L Goetz AE Kuebler WM 《Journal of neuroscience methods》2002,114(2):107-117
Reflection near infrared spectroscopy (reNIRS) has been proposed as a novel technique for the measurement of absolute values of total hemoglobin (tHb), oxygenated hemoglobin (oxHb), hemoglobin saturation (SO2), and cytochrome aa3 oxidation status (oxCyt aa3) in living tissue. In this study, we evaluated reNIRS during physiological cerebral blood flow conditions in rats (n=6) and during the induction of global cerebral ischemia in gerbils (n=6). ReNIRS parameters were assessed over the exposed cerebral cortex and compared to regional cerebral blood flow (rCBF) data obtained by laser Doppler flowmetry. Under physiological conditions, reNIRS measurements reflected the large intra- and interindividual variability of oxHb and tHb in the brain. The absolute values obtained by reNIRS for tHb (6.3 +/- 1.7 mg/ml), oxHb (3.7 +/- 1.1 mg/ml), and SO2 (61 +/- 5%) matched expected values. In contrast, measurements of oxCyt aa3 were unstable and results unreliable. reNIRS reliably detected cerebral ischemia, verified by a reduction of rCBF to 11% of baseline. tHb dropped to 74 +/- 7% of baseline (P<0.001), reflecting ischemic microvascular vasoconstriction. oxHb and SO2 dropped to expected near-zero values (2 +/- 4 and 3 +/- 5% of baseline, respectively; P<0.001). We conclude that reNIRS provides reliable and reproducible absolute values for brain tissue tHb, oxHb, and SO2 in small rodents. Determination of physiological values requires measurements at multiple locations, while cerebral ischemia is reliably detected by continuous recordings at a single location. 相似文献
116.
Tardive dyskinesia caused by antipsychotic treatment is a severe problem not only in the management of schizophrenia, but also of affective disorders. Vitamin E monotherapy has been used in schizophrenic patients with tardive dyskinesia. Pharmacologists warn against high dosage of vitamin E because of its pro-oxidative effects on low-density lipoprotein with consecutive cardiac risks. Addition of vitamin C probably reduces this risk because of its interactions with vitamin E, i.e. vitamin C reduces vitamin E radicals formed when vitamin E scavenges the oxygen radicals. We have therefore tested the safety and efficacy of combining vitamin C and E in a sample of patients with affective disorders and tardive dyskinesia who had previously been treated with antipsychotics due to psychotic symptoms. In all 6 patients, a reduction of tardive symptomatology was seen. In our sample, no side effects were observed. Further studies on this combination therapy are suggested. 相似文献
117.
118.
Diffuse cortical reduction of neuronal activity in unipolar major depression: a retrospective analysis of 337 patients and 321 controls 总被引:1,自引:0,他引:1
Nikolaus S Larisch R Beu M Vosberg H Müller-Gärtner HW 《Nuclear medicine communications》2000,21(12):1119-1125
Reduction of neuronal activity in frontocortical and limbic circuits is considered a characteristic of depression. We aimed to test this hypothesis by pooling all available data from experimental literature. All investigations were included comparing regional cerebral blood flow (rCBF) or glucose metabolism (rCMRGlc) between acutely depressed unipolar major depressive patients and healthy controls. For cortical and subcortical regions we computed the percentage difference between depressives (n = 337) and controls (n = 321). In patients with unipolar major depression rCBF and rCMRGlc were lowered in left (-4.4%, P = 0.022) and right frontal (-3.2%, P = 0.053), left (-1.7%, P = 0.061) and right temporal (-3.0%, P=0.003), left (-6.5%, P = 0.002), and right parietal (-8.8%, P=0.001), and left (-6.6%, P = 0.083) and right occipital cortex (-4.2%, P = 0.02). Moreover, there were reductions in left (-6.3%, P = 0.029) and right basal ganglia (-4.8%, P = 0.002), left (-3.4%, P = 0.114) and right thalamus (-3.1%, P = 0.036), and left limbic system (-2.2%, P = 0.127). Parameters were increased by 1.0% (P = 0.714) only in the right limbic system. There were no hemispheric asymmetries (P > 0.05). Moreover, there was no indication for an anterior-posterior gradient (P > 0.05), and thus no 'hypofrontality'. In contrast to the current view, the data indicate a diffuse cortical rather than regionalized reduction of neuronal activity in unipolar major depression. 相似文献
119.
Claudia Auw-Haedrich Rainer Sundmacher Nikolaus Freudenberg Helga Spelsberg Nicolas Feltgen Philip Maier Thomas Reinhard 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2006,244(1):96-103
Background
p63 is a homologue of the tumour suppressor gene p53, which is expressed in human basal squamous epithelium. Some investigators maintain that p63 plays a role in the development of squamous epithelium and, despite its homology to p53, it is considered to act as an oncogene. This study investigated the expression of p63 in conjunctival intraepithelial neoplasia of different grades, and conjunctival squamous cell carcinoma and its correlation
to the proliferation marker MIB-1.
Material and methods Seventeen conjunctival specimens excised with the suspicion of either conjunctival intraepithelial neoplasia (CIN) or squamous
cell carcinoma were diagnosed histologically as follows: 2 squamous cell carcinomas of the conjunctiva, 2 CIN grade I, 3 CIN
grade II, 7 CIN grade III, 2 CIN with beginning invasion and 1 normal conjunctiva with no dysplasia. Sixteen microscopically-normal
postmortem conjunctival specimens and normal conjunctiva, CIN and carcinoma specimens were stained immunohistochemically with
antibodies against p63 and MIB-1. At least 500 cells per specimen were counted and the percentage of positively-stained cells of each antibody was
calculated.
Results A mean of 80% (57–89%) of the dysplastic cells from the CIN specimens stained positively with antibodies against p63, especially in the lower two-thirds of the epithelium, statistically significantly more compared with the normal specimens
(9–55%, mean 36%, p<0.001). Nevertheless, we did not find a correlation between the percentage of p63-positive cells and the differentiation grade of the malignant specimens. MIB-1 positivity was shown by 0–1% of the cells
in the normal postmortem controls, by 3–30% (mean 12%) of the cells in the basal and occasionally in the middle layer of the
CIN specimens, and 16–61% (mean 23%) in the carcinoma specimens.
Conclusion In conjunctival intraepithelial neoplasia and squamous cell carcinoma of the conjunctiva, p63 is preferentially expressed in the immature dysplastic epithelial cells. Its staining does not correlate with MIB-1-expression,
and therefore does not appear to be linked to cell proliferation. 相似文献
120.
Epidemiologic aspects of cancer prevention in Germany 总被引:4,自引:0,他引:4
Becker N 《Journal of cancer research and clinical oncology》2001,127(1):9-19
In Germany, as in other highly industrialized countries, cancer is the second most common cause of death. With approximately
210,000 individuals dying each year from malignant tumours, roughly one in four deaths in Germany can currently be attributed
to cancer. Only in the past few years has there been a slow decline in the age-standardized mortality rates for cancer, even
among men. This follows a long period of some decades, during which the mortality steadily increased and then persisted at
a high level. The reversal, however, does not mean that the situation is no longer a cause for concern. In fact, for the most
common cause of death, namely the cardiovascular diseases, a much greater decrease in mortality has been observed for many
years now. If this trend continues, cancer could become the largest killer in another 15 to 20 years. On the other hand, we
have been aware since the end of the 1960s that the majority of cancers are caused by environmental influences and are thus,
in principle, avoidable. In the present contribution we present: (a) the fundamental arguments to support the thesis that
a large proportion of cancers, and of cancer deaths, could be avoided; and (b) an estimate for Germany of both the theoretical
potential of primary cancer prevention and also the practically attainable potential. The estimates are based on very conservative
assumptions. They yield, for the theoretical potential, values in the range 43–65% and for the reduction actually obtainable
in the medium term due to primary prevention, values of 18–31%.
Received: 9 March 1999 / Accepted: 26 April 2000 相似文献