全文获取类型
收费全文 | 5341篇 |
免费 | 243篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 49篇 |
儿科学 | 97篇 |
妇产科学 | 47篇 |
基础医学 | 639篇 |
口腔科学 | 135篇 |
临床医学 | 366篇 |
内科学 | 1377篇 |
皮肤病学 | 199篇 |
神经病学 | 328篇 |
特种医学 | 225篇 |
外科学 | 929篇 |
综合类 | 25篇 |
预防医学 | 174篇 |
眼科学 | 53篇 |
药学 | 357篇 |
中国医学 | 10篇 |
肿瘤学 | 624篇 |
出版年
2023年 | 27篇 |
2022年 | 88篇 |
2021年 | 124篇 |
2020年 | 59篇 |
2019年 | 97篇 |
2018年 | 104篇 |
2017年 | 98篇 |
2016年 | 114篇 |
2015年 | 135篇 |
2014年 | 146篇 |
2013年 | 185篇 |
2012年 | 292篇 |
2011年 | 330篇 |
2010年 | 217篇 |
2009年 | 151篇 |
2008年 | 287篇 |
2007年 | 301篇 |
2006年 | 269篇 |
2005年 | 285篇 |
2004年 | 272篇 |
2003年 | 261篇 |
2002年 | 232篇 |
2001年 | 147篇 |
2000年 | 135篇 |
1999年 | 145篇 |
1998年 | 62篇 |
1997年 | 67篇 |
1996年 | 41篇 |
1995年 | 35篇 |
1994年 | 34篇 |
1993年 | 20篇 |
1992年 | 78篇 |
1991年 | 64篇 |
1990年 | 70篇 |
1989年 | 69篇 |
1988年 | 62篇 |
1987年 | 60篇 |
1986年 | 57篇 |
1985年 | 59篇 |
1984年 | 53篇 |
1983年 | 33篇 |
1980年 | 15篇 |
1979年 | 25篇 |
1974年 | 13篇 |
1973年 | 16篇 |
1971年 | 27篇 |
1970年 | 24篇 |
1969年 | 16篇 |
1967年 | 19篇 |
1966年 | 20篇 |
排序方式: 共有5634条查询结果,搜索用时 46 毫秒
41.
A cis-diamminedichloroplatinum (CDDP)-selected cell line (MT-R10) was induced by continuous exposure of an in vitro passaged cell line (MT-P) established from a transplantable rat malignant fibrous histiocytoma (MFH-MT) to CDDP. MT-R10, capable of proliferating in the presence of 1.0 microgram CDDP/ml, was passaged in CDDP-free medium. The doubling time of MT-R10 at passage 10 (MT-R10/10) was almost the same as that of MT-P, being 22.3 and 25.5 h, respectively. The concentration of CDDP required for 50% inhibition of MT-R10/10 proliferation was two-fold higher than that of MT-P. MT-R10 consisted of round, epithelial-type cells arranged in compact sheets. Ultrastructurally, MT-R10 had numerous free ribosomes, some mitochondria, and other poorly developed cytoplasmic organelles suggesting its undifferentiated nature. MT-R10 showed no reaction for acid phosphatase or non-specific esterase. Tumors induced in syngeneic rats by inoculation with MT-R10 consisted of small, round, undifferentiated cells with scanty cytoplasm. They showed organoid and trabecular patterns, and were often arranged in compact sheets. The neoplastic cells showed no reaction for any of the histiocytic lysosomal and antigenic markers tested, but exhibited a strong reaction for alkaline phosphatase. Bone formation was often observed in the tumors. These observations suggest that CDDP-selected, undifferentiated cells may have osteogenic potential and may be one of the progenitor cells of MFH-MT. 相似文献
42.
Riki Okeda Makoto Shibutani Takashi Matsuo Tayoko Tajima 《Pathology international》1992,42(5):316-324
The pathogenesis of fetal brain damage caused by acute maternal hypoglycemia was investigated experimentally in cats: profound hypoglycemia (blood glucose concentration:less than 30 mg/dl) was induced in 12 pregnant cats at various stages of gestation by intravenous bolus injections of insulin. Maximal hypoglycemia was attained within 2 3 h, although the grade and duration in individual cats varied. The EEGs of all of seven maternal cats examined showed an increased frequency of slow high-voltage waves as hypoglycemia progressed, eventually becoming flat in 3 for a maximum period of 20 min. Some fetuses showed severe neuropathological changes, such as infarction or intrauterine death. Subventricular soften ing, cortical hemorrhage and ischemic neuronal changes also occurred, being distributed symmetrically in the para-sagittal areas of the cerebrum, basal ganglia, thalamus and tegrnentum of the brainstem. In general, these patho logical changes were more marked in fetuses and neonates than in the maternal cats, in which only ischemic neuronal changes were present, and may have been due to fetal systemic hypotension and cerebral ischemia induced by hypoglycemia. In maternal cats, the distribution of neu rons showing ischemic changes was widest in the cerebral cortex, and some were also present in the dentate gyri of the hippocampus. Moreover, ultrastructural examination of the ischemic neurons in maternal cats, unlike those of the fetuses, showed no mitochondrial swelling. Therefore, the distribution and ultrastructural nature of the ischemic neurons found in the maternal cats were considered to be characteristic of hypoglycemia, as proposed by Agardh et al . (1980). Acta Pathol Jpn 42 : 316–324, 1992. 相似文献
43.
Analysis of the steroidogenic acute regulatory protein (StAR) gene in Japanese patients with congenital lipoid adrenal hyperplasia 总被引:1,自引:0,他引:1
Nakae J; Tajima T; Sugawara T; Arakane F; Hanaki K; Hotsubo T; Igarashi N; Igarashi Y; Ishii T; Koda N; Kondo T; Kohno H; Nakagawa Y; Tachibana K; Takeshima Y; Tsubouchi K; Strauss JF rd; Fujieda K 《Human molecular genetics》1997,6(4):571-576
Genomic DNA from 19 Japanese patients with congenital lipoid adrenal
hyperplasia (lipoid CAH) representing 16 different families was examined to
identify the genetic alterations of steroidogenic acute regulatory protein
(StAR). Ten of 19 patients had a 46,XX karyotype and nine had a 46,XY
karyotype. Six of the 46,XX patients have experienced spontaneous pubertal
changes including breast development and irregular menstruation whereas
none of the 46,XY subjects displayed pubertal changes. Eight different
mutations were identified. Sixteen patients were either homozygotes or
compound heterozygotes for the Q258X mutation. The seven other mutations
identified were 189delG, 246insG, 564del13bp, 838delA, Q212X, A218V and
M225T. The 189delG, 246insG, 546del13bp and Q212X mutants encode truncated
proteins. COS-1 cells transfected with expression vectors encoding cDNAs
for the mutant StAR proteins which affect the C-terminus, 838delA, A218V
and Q258X, exhibited no steroidogenesis enhancing activity. However, the
M225T mutant retained some steroidogenic activity. The patient with the
M225T mutation had late onset of this disorder and some capacity to secrete
testosterone in response to hCG. These findings suggest: (i) that the Q258X
mutation can be used as a genetic marker for the screening of Japanese for
lipoid CAH, (ii) that the C-terminus of StAR plays an important role in the
protein's activity and (iii) that there are differences in the extent of
functional impairment of the testis and ovaries in lipoid CAH.
相似文献
44.
Jain AN Tokuyasu TA Snijders AM Segraves R Albertson DG Pinkel D 《Genome research》2002,12(2):325-332
DNA microarrays are now widely used to measure expression levels and DNA copy number in biological samples. Ratios of relative abundance of nucleic acids are derived from images of regular arrays of spots containing target genetic material to which fluorescently labeled samples are hybridized. Whereas there are a number of methods in use for the quantification of images, many of the software systems in wide use either encourage or require extensive human interaction at the level of individual spots on arrays. We present a fully automatic system for microarray image quantification. The system automatically locates both subarray grids and individual spots, requiring no user identification of any image coordinates. Ratios are computed based on explicit segmentation of each spot. On a typical image of 6000 spots, the entire process takes less than 20 sec. We present a quantitative assessment of performance on multiple replicates of genome-wide array-based comparative genomic hybridization experiments. By explicitly identifying the pixels in each spot, the system yields more accurate estimates of ratios than systems assuming spot circularity. The software, called, runs on Windows platforms and is available free of charge for academic use. 相似文献
45.
The effect of calcium ion concentration on osteoblast viability, proliferation and differentiation in monolayer and 3D culture 总被引:9,自引:0,他引:9
Maeno S Niki Y Matsumoto H Morioka H Yatabe T Funayama A Toyama Y Taguchi T Tanaka J 《Biomaterials》2005,26(23):4847-4855
Our research group aims to develop an osteochondral composite using type II collagen gel with hydroxyapatite (HAp) deposited on one side. Soaking gels in Ca2+ and phosphate solution is indispensable to HAp deposition, so relationships between cell behavior and Ca2+ concentration were examined in two- and three-dimensional cultures. The present results indicate that 2-4 mM Ca2+ is suitable for proliferation and survival of osteoblasts, whereas slightly higher concentrations (6-8 mM) favor osteoblast differentiation and matrix mineralization in both 2- and 3-dimensional cultures. Higher concentrations (>10 mM) are cytotoxic. Purely from the perspective of calcium deposition, higher concentrations lead to increased accumulation of Ca2+. Culturing cells in phosphate-containing gel in media with Ca2+ also leads to time-dependent formation of HAp in the gel. Considering the viability of embedded cells, culturing scaffolds in media with Ca2+ concentrations around 5mM is useful for both HAp deposition and osteoblast behavior. 相似文献
46.
Tetsuya Murata Toshihiko Soga Kazuhiro Tajima Kaoru Saito Yoshinori Komeda Sergio Ossamu Loshii Taizo Shiraishi Teruyo Sakakura Ryuichl Yatani 《Pathology international》1994,44(2):138-144
Sarcomatoid carcinoma is a rare variant of malignant tumor arising from the urinary tract. This tumor had been termed carcinosarcoma because of its carcinomatous and sarcomatous components. There is still some confusion in the terminology between true carcinosarcoma and sarcomatoid carcinoma; however, the latter is now regarded as primarily a malignant epithelial tumor with pseudosarcomatous transformation.
Four cases of sarcomatoid carcinoma arising from the urinary tract are reported. The patients were a 77 year old female, and three males aged 62, 69 and 80 years. All but the eldest patient complained of gross hematurla. Surgical removal was performed in the younger three cases, and an autopsy was done in the remaining case. All the tumors were macroscopically polypoid. Histopathologic examination revealed fasciculated spindle-cell tumors with myxold stroma or malignant fibrous histiocytoma-like spindle cell tumors. The epithelial nature was proven in these sarcomatous cells by immunohistochemical andlor electron-microscopic examinations. Only a small amount of squamous cell carcinoma components was also evident in the latter three cases. Although the younger three patients were alive at 44, 23 and 39 months'follow-up, respectively, constant careful monitoring Is recommended. 相似文献
Four cases of sarcomatoid carcinoma arising from the urinary tract are reported. The patients were a 77 year old female, and three males aged 62, 69 and 80 years. All but the eldest patient complained of gross hematurla. Surgical removal was performed in the younger three cases, and an autopsy was done in the remaining case. All the tumors were macroscopically polypoid. Histopathologic examination revealed fasciculated spindle-cell tumors with myxold stroma or malignant fibrous histiocytoma-like spindle cell tumors. The epithelial nature was proven in these sarcomatous cells by immunohistochemical andlor electron-microscopic examinations. Only a small amount of squamous cell carcinoma components was also evident in the latter three cases. Although the younger three patients were alive at 44, 23 and 39 months'follow-up, respectively, constant careful monitoring Is recommended. 相似文献
47.
Assarsson E Kambayashi T Persson CM Ljunggren HG Chambers BJ 《Molecular immunology》2005,42(4):419-423
NK cells have primarily been defined by their ability to kill infected cells, tumor cells and some normal cells expressing low levels of MHC class I molecules. NK cells have also been shown to affect adaptive immune responses by their production of both pro- and anti-inflammatory cytokines. Recently it has been shown that adaptive immune responses can be enhanced or maintained also through direct lymphocyte-lymphocyte interactions. One of these interactions was identified to occur between 2B4 and CD48, where 2B4 acted as a co-stimulatory ligand for both NK cells and T cells. In the current article, we discuss the role of 2B4 in the development of adaptive immune responses and the role of NK-T cell interactions in these responses. 相似文献
48.
Antifungal activities of tacrolimus and azole agents against the eleven currently accepted Malassezia species 总被引:5,自引:0,他引:5
Sugita T Tajima M Ito T Saito M Tsuboi R Nishikawa A 《Journal of clinical microbiology》2005,43(6):2824-2829
The lipophilic yeast Malassezia is an exacerbating factor in atopic dermatitis (AD) and colonizes the skin surface of patients with AD. With the goal of reducing the number of Malassezia cells, we investigated the antifungal activities of a therapeutic agent for AD, tacrolimus, and the azole agents itraconazole and ketoconazole against Malassezia species in vitro. We examined 125 strains of the 11 currently accepted Malassezia species by using the agar dilution method. All strains of the 11 Malassezia species were very susceptible to both azole agents, with MICs ranging from 0.016 to 0.25 mug/ml. Tacrolimus had antifungal activities against half of the strains, with MICs ranging from 16 to 32 mug/ml. Two of the major cutaneous floras, Malassezia globosa and Malassezia restricta, have several genotypes in the intergenic spacer region of the rRNA gene; the azole agents had slightly higher MICs for specific genotype strains of both microorganisms. A combination of azole agents and tacrolimus had a synergistic effect against Malassezia isolates, based on a fractional inhibitory index of 0.245 to 0.378. Our results provide the basis for testing these agents in future clinical trials to reduce the number of Malassezia cells colonizing the skin surface in patients with AD. 相似文献
49.
Lack of association between DNA base excision repair gene XRCC1 Gln399Arg polymorphism and risk of malignant lymphoma in Japan 总被引:2,自引:0,他引:2
Matsuo K Hamajima N Suzuki R Andoh M Nakamura S Seto M Morishimae Y Tajima K 《Cancer Genetics and Cytogenetics》2004,149(1):77-80
Growing evidence suggests that the polymorphism of DNA base excision repair gene XRCC1 Arg399Gln is associated with altered DNA repair proficiency and subsequent cancer susceptibility; however, no evidence is available for malignant lymphoma. We therefore conducted a case-control study (372 cases, 500 controls) to evaluate links with malignant lymphoma risk in Japan. The risk was evaluated in terms of odds ratio (OR) and 95% confidence interval (CI) adjusted for age and sex in an unconditional logistic regression model. There was no statistical risk change with the Arg/Gln (adjusted OR 0.89; 0.65-1.23, P = 0.492) or the Gln/Gln (0.57; 0.27-1.17, P = 0.127) compared with the Arg/Arg of the XRCC1 Arg399Gln polymorphism. The results were unchanged in analyses according to histological subtype (diffuse large lymphoma, follicular lymphoma, low-grade lymphoma of mucosa-associated lymphoid tissue, and others). These data suggest that XRCC1 Gln399Arg polymorphism plays a limited role in lymphomagenesis. Further study on the interaction between the polymorphism and environmental exposure is required. 相似文献
50.
Akiko Hori Masahiro Kami Sung-Won Kim Aki Chizuka Rie Kojima Osamu Imataki Michiyo Sakiyama Tamae Hamaki Yasushi Onishi Noriko Usubuchi Yukiko Kishi Naoko Murashige Kinuko Tajima Shigesaburo Miyakoshi Yuji Heike Shigeru Masuo Shuichi Taniguchi Yoichi Takaue 《Biology of blood and marrow transplantation》2004,10(1):65-72
Little information is available on the clinical characteristics of infectious complications that occur in the early period after reduced-intensity stem cell transplantation (RIST). We retrospectively investigated the clinical features of neutropenic fever and infectious episodes within 30 days after RIST in 76 patients who had received fluoroquinolones as part of their antibacterial prophylaxis. Preparative regimens included cladribine 0.66 mg/kg or fludarabine 180 mg/m2 plus busulfan 8 mg/kg. All but 1 patient survived 30 days after transplantation, and 75 patients (99%) became neutropenic within a median duration of 9 days. Neutropenic fever was observed in 29 patients (38%), and bacterial infection was confirmed in 15 (20%) of these, including bacteremia (n = 13), bacteremia plus pneumonia (n = 1), and urinary tract infection (n = 1). The causative organisms were gram-positive (n = 9) and gram-negative organisms (n = 7), with a mortality rate of 6%. Neither viral nor fungal infection was documented. Multivariate analysis showed that the presence of neutropenia at the initiation of preparative regimens was an independent risk factor for subsequent documented bacterial infections (P =.026; 95% confidence interval, 1.25-35.1). We conclude that neutropenic fever and bacteremia remain common complications in RIST. 相似文献