全文获取类型
收费全文 | 5879篇 |
免费 | 320篇 |
国内免费 | 183篇 |
专业分类
耳鼻咽喉 | 47篇 |
儿科学 | 93篇 |
妇产科学 | 78篇 |
基础医学 | 568篇 |
口腔科学 | 114篇 |
临床医学 | 424篇 |
内科学 | 714篇 |
皮肤病学 | 64篇 |
神经病学 | 437篇 |
特种医学 | 177篇 |
外科学 | 633篇 |
综合类 | 536篇 |
预防医学 | 554篇 |
眼科学 | 103篇 |
药学 | 1247篇 |
中国医学 | 385篇 |
肿瘤学 | 208篇 |
出版年
2024年 | 25篇 |
2023年 | 144篇 |
2022年 | 250篇 |
2021年 | 291篇 |
2020年 | 239篇 |
2019年 | 245篇 |
2018年 | 247篇 |
2017年 | 194篇 |
2016年 | 217篇 |
2015年 | 192篇 |
2014年 | 392篇 |
2013年 | 410篇 |
2012年 | 301篇 |
2011年 | 299篇 |
2010年 | 208篇 |
2009年 | 224篇 |
2008年 | 239篇 |
2007年 | 208篇 |
2006年 | 223篇 |
2005年 | 175篇 |
2004年 | 144篇 |
2003年 | 130篇 |
2002年 | 96篇 |
2001年 | 94篇 |
2000年 | 78篇 |
1999年 | 74篇 |
1998年 | 59篇 |
1997年 | 49篇 |
1996年 | 51篇 |
1995年 | 72篇 |
1994年 | 54篇 |
1993年 | 46篇 |
1992年 | 39篇 |
1991年 | 51篇 |
1990年 | 58篇 |
1989年 | 43篇 |
1988年 | 46篇 |
1987年 | 42篇 |
1986年 | 36篇 |
1985年 | 49篇 |
1984年 | 67篇 |
1983年 | 24篇 |
1982年 | 48篇 |
1981年 | 47篇 |
1980年 | 31篇 |
1979年 | 20篇 |
1978年 | 19篇 |
1977年 | 32篇 |
1976年 | 17篇 |
1973年 | 10篇 |
排序方式: 共有6382条查询结果,搜索用时 31 毫秒
41.
Kenji Sano 《Pathology international》1988,38(10):1241-1253
White male rabbits, weighing about 3 kg, were injected intravenously with 5 ml of 0.1% saponin solution dissolved in physiological saline once a week for six months. The sequential histological changes in the kidneys were observed by repeated biopsies and, in addition, the animals were subjected to necropsy for light and electron microscopic examinations. Amyloid protein was purified from the animal tissues, estimated at approximately 6,300 daltons in molecular weight by SDS-PAGE and considered as an AA type protein based on its amino acid sequence study. The antibody against the purified amyloid protein was produced in guinea pigs and was used for immunohistochemical studies. The deposition of amyloid started initially in mesangial matrices and subendothelial regions of the glomeruli, but at the end the spleen, kidney and bowels were found to be frequent sites of deposition. The amyloid deposited in the tissues was specifically positive by the indirect immunohistochemistry using the prepared antibody. This antibody also reacted positively to human materials with secondary amyloidosis. These results indicate that amyloidosis induced by saponin is a good model of secondary amyloidosis. 相似文献
42.
B. A. Sabel G. E. Schneider 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1988,71(2):365-376
Summary The effects of exogenous gangliosides on sprouting of optic tract axons was studied in hamsters which, after a right tectal lesion on the day after birth (P1), had an abnormal retinotectal projection from the left eye to the left superior colliculus (SC). Sprouting of these axons was induced by removing the competing input by right eye removal on postnatal day 9 (P9). Intraperitoneal GM1, given daily and started on P9, significantly stimulated the sprouting response. This was demonstrated by Fink-Heimer silver staining of anterograde axonal degeneration three days after the left eye was removed on P36. Terminal fields in the left SC were, in average, twice as large compared to controls. An estimate of the total number of terminals (silver stained particles) revealed a value of 7.9×106 for GM1 and 3.2×106 for control hamsters, respectively. Diencephalic structures which also receive collateral input from the sprouting optic tract did not show any alterations in the size of the terminal field due to GM1-treatment, suggesting that, in vivo, gangliosides fail to initiate sprouting in areas that have not previously been denervated. Unexpectedly, GM1-treated hamsters also had significantly smaller right SC damage and less left damage near the midline. Subsequent reanalysis of the data based on a lesion-matching procedure indicates that effects on reducing atrophy were independent of the GM1-enhanced sprouting of retinofugal axons. These findings provide the first direct evidence that exogenous GM1 stimulates lesion-induced axon sprouting in the mammalian brain. 相似文献
43.
Visualizing metabolic changes in breast-cancer tissue using 1H-NMR spectroscopy and self-organizing maps 总被引:8,自引:0,他引:8
In-vitro NMR spectroscopic examinations of tissue extracts can be combined with appropriate pattern-recognition and visualization techniques in order to monitor characteristic metabolic differences between tissue classes. In the present study, such techniques are applied to a set of 88 breast-tissue samples with the intention of identifying typical differences between various tissue classes. The set contains 49 breast-tumor samples of various tumor grades and 39 samples of healthy tissue. The metabolite compositions of the tissue extracts were investigated using a dual extraction technique and high-resolution (1)H-NMR spectroscopy. The spectra of the hydrophilic and the lipophilic compounds were assigned to three groups according to different malignancy grades of the respective tissue samples. The group characteristics were analyzed using the k-nearest-neighbor method and self-organizing-map visualizations. The results show an increase of UDP-hexose, phosphocholine and phosphoethanolamine concentrations according to the tumor grade. Higher concentrations of taurine were detected in the malignant samples. Myo-inositol and glucose content were elevated in control samples compared with malignant tissue. Both compounds also characterized different subgroups in the pool of unaffected tissue samples depending upon fat content or fibrosis. Several lipid metabolites showed a characteristic elevation with high malignancy. 相似文献
44.
M. Middeke E. Mika M. A. Schreiber B. Beck B. Wächter H. Holzgreve 《Journal of molecular medicine (Berlin, Germany)》1989,67(14):713-716
Summary Ambulatory 24 hour blood pressure measurements were performed in 21 patients with various forms of secondary hypertension and were compared with the blood pressure profile of a matched group of patients with primary hypertension. Patients with renovascular (n=8) and renoparechymal hypertension (n=8), and with primary hyperaldosteronism (n=4) showed no significant fall in systolic blood pressure during the sleeping period (00-03 a.m.) and in systolic and diastolic blood pressure in the early morning (06 a.m.) as compared with essential hypertensives. However, in a single case of hypertension due to coarctation of the aorta the 24 hour blood pressure profile is not different from essential hypertension.Thus, ambulatory 24 hour blood pressure recording is a good method for screening secondary forms of hypertension. 相似文献
45.
Kantele A Savilahti E Tiimonen H Iikkanen K Autio S Kantele JM 《European journal of immunology》2003,33(12):3275-3283
In contrast to T cells, information on skin-homing B cells expressing the cutaneous lymphocyte antigen (CLA) is sparse. CLA expression on human B cells was investigated among circulating immunoglobulin-secreting cells (ISC) and among antigen-specific antibody-secreting cells (ASC) elicited by parenteral, oral or rectal primary immunization, or by parenteral or oral secondary immunization with Salmonella typhi Ty21a. CLA expression was examined by combining cell sorting with an enzyme-linked immunospot assay. Among all ISC, the proportion of CLA(+) cells was 13-21%. Parenteral immunization induced antigen-specific ASC of which 13% were CLA(+), while oral and rectal immunizations were followed by only 1% of CLA(+) ASC (p<0.001). Oral re-immunization was followed by an up-regulation of CLA (34-48%) regardless of the route of priming. Parenteral re-immunization elicited ASC of which 9-14% were CLA(+). In conclusion, the expression of CLA on human effector B cells depends on the site of antigen encounter: intestinal stimulation elicits cells with no CLA, while parenteral encounter elicits significant numbers of CLA(+) cells. Even though primary antigen encounter in the intestine failed to stimulate CLA expression, up-regulation of CLA was found upon intestinal antigen re-encounter. These findings may be of relevance in the pathogenesis of some cutaneous disorders. 相似文献
46.
初中生主观幸福感与人格特征的关系研究 总被引:19,自引:2,他引:19
目的:探讨初中生主观幸福感与人格特征之间的关系。方法:采用中学生主观幸福感量表和EPQ对283名中学生进行调查。结果:(1)初中生的主观幸福感水平在中等程度以上,体验到的正性情感较多,但是仍有一定比例的学生体验到较强的不幸福感。男女生在总体幸福感、家庭满意感、自我满意感、同伴交往满意感和生活条件满意感上存在显著的差异,女生得分均高于男生。(2)总体幸福感及各因子与精神质和神经质显著负相关,与内外向显著正相关。结论:初中生主观幸福感与人格特征关系密切。 相似文献
47.
Kalinski T Krueger S Pelz AF Wieacker P Hartig R Röpke M Schneider-Stock R Dombrowski F Roessner A 《Virchows Archiv : an international journal of pathology》2005,446(3):287-299
The permanent human cell line C3842 was established from a secondary chondrosarcoma in a typical case of Olliers disease. In the present study, we analyzed the morphological, cytogenetic and molecular biological characteristics of the cultured cells in comparison with the original tumor and investigated the invasion properties of the tumor model using functional imaging of proteolysis, matrigel assay and chick chorioallantoic membrane assay. C3842 cells exhibit the typical features of malignant cartilage tumor cells in vitro, including the expression of collagen types II, IX, XI and aggrecan. The proteolytic ability of C3842 cells is attributed to the expression of several proteases, such as cathepsin B, urokinase plasminogen activator and matrix-metalloproteinase-2, which enable the cells to degrade collagen type I and to permeate matrigel matrix. In accordance with the biological features in vivo, C3842 cells are not able to invade through the epithelium of the chick chorioallantoic membrane. In conclusion, the cell line C3842 provides the first model of a secondary chondrosarcoma in Olliers disease in vitro, which is characterized by distinct features of such malignant cartilage tumors. 相似文献
48.
H.-G. Mergenthaler M. Fink H. Sauer R. Bartl W. Wilmanns 《Journal of molecular medicine (Berlin, Germany)》1989,67(1):42-46
Summary For years, brown tumors have been considered to be a characteristic of primary hyperparathyroidism. However, since 1963 several reports indicate the incidence of brown tumors in patients with renal secondary hyperparathyroidism to be 1.5%–1.7%. The appearance of multiple brown tumor lesions is rather uncommon in secondary hyperparathyroidism which is also true for malabsorption as its cause. We report on a 56-year-old man presenting with pain in the bones and multiple osteolyses. A bone biopsy specimen and the laboratory examinations were indicative of secondary hyperparathyroidism caused by malabsorption most likely due to Billroth's II/I gastric resection. Thus, the patient's osteolyses represent brown tumors which have been induced by nutritional secondary hyperparathyroidism. 相似文献
49.
Ulrich Tibes Edeltraud Haberkorn-Butendeich Frithjof Hammersen 《Pflügers Archiv : European journal of physiology》1977,368(3):195-202
Summary The effect of muscle contraction on lymphatic and plasma [K+], [Na+], [Ca2+], [Mg2+], [Cl–], [Pi], [lactate] ([Lac–]); [creatine] ([Cr]), ideal osmolality (OSM), and [protein] was evaluated in femoral venous blood and lymph specimens sampled from the calf muscles of rabbits before, in the course of, and after contractions. In addition, total [K+], [Na+], [Ca2+], [Mg2+], [Cl–], and [H2O] were analyzed in the muscle tissue. To facilitate lymph sampling both hind limbs were passively flexed and extended, in imitation of natural running movements, by an electrically driven crank. The muscles of one side also performed superimposed rhythmic isotonic contractions. Before contractions, lymphatic [K+], [Na+], [Ca2+], [Mg2+], [Lac–], [Cr], and OSM did not significantly differ from corresponding femoral venous concentrations, [Cl–], and [Pi] were significantly higher, [protein] significantly lower in the lymph than in the plasma. During contractions lymphatic [K+], OSM, [Lac–], and [Pi] were raised significantly more in the lymph compared with the plasma concentrations. [Na+], [Cl–], [Ca2+], and [Mg2+] showed only small changes in the course of contractions and thereafter, and they were altered in a similar way in the lymph and plasma. It was suggested that lymphatic and interstitial concentrations were in equilibrium. Comparing inactive with active muscles, the latter lost K+ but gained Na+, Cl–, and H2O, whereas minimal changes occurred in the [Ca2+] and [Mg2+]. The changes were discussed in connection with the hypothesis that electrolyte shifts might be involved in the activation of the muscular non-proprioceptive interstitial nerve endings which appear to play a role in reflexogenic cardiovascular and respiratory control.A preliminary report of this work has been given elsewhere [33]Supported by Deutsche Forschungsgemeinschaft 相似文献
50.
Riitta Hari Ritva Hänninen Timo Mäkinen Veikko Jousmäki Nina Forss Mika Seppä Oili Salonen 《Neuroscience letters》1998,240(3):998-134
We describe patient E.P. who occasionally perceives a ‘ghost' hand which copies the previous positions of the left hand with a 0.5–1 min time lag, but follows the movement patterns of the right hand. The symptoms started after an operation of a ruptured aneurysm, followed by an infarction of the right frontal lobe; E.P. also has a previously lesioned corpus callosum. Neuromagnetic recordings revealed that activity of the left secondary somatosensory cortex was strongly suppressed during the ghost arm percept, thereby providing an objective correlate for E.P.'s sensations. We conclude that simultaneous mental contents about body scheme may be based on neural information extracted at considerably different times, resulting in fragmentation of bodily awareness. 相似文献