首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17960篇
  免费   1090篇
  国内免费   80篇
耳鼻咽喉   289篇
儿科学   409篇
妇产科学   293篇
基础医学   2598篇
口腔科学   1852篇
临床医学   1467篇
内科学   3708篇
皮肤病学   405篇
神经病学   1323篇
特种医学   507篇
外科学   1950篇
综合类   80篇
一般理论   4篇
预防医学   2001篇
眼科学   183篇
药学   1322篇
中国医学   186篇
肿瘤学   553篇
  2023年   158篇
  2022年   445篇
  2021年   661篇
  2020年   450篇
  2019年   571篇
  2018年   726篇
  2017年   587篇
  2016年   559篇
  2015年   714篇
  2014年   873篇
  2013年   1006篇
  2012年   1481篇
  2011年   1650篇
  2010年   899篇
  2009年   680篇
  2008年   1064篇
  2007年   1074篇
  2006年   859篇
  2005年   740篇
  2004年   612篇
  2003年   518篇
  2002年   433篇
  2001年   288篇
  2000年   261篇
  1999年   208篇
  1998年   132篇
  1997年   108篇
  1996年   101篇
  1995年   85篇
  1994年   79篇
  1993年   68篇
  1992年   104篇
  1991年   109篇
  1990年   75篇
  1989年   73篇
  1988年   75篇
  1987年   57篇
  1986年   57篇
  1985年   48篇
  1984年   37篇
  1983年   48篇
  1981年   27篇
  1980年   34篇
  1979年   32篇
  1977年   27篇
  1976年   18篇
  1973年   20篇
  1970年   17篇
  1968年   32篇
  1966年   16篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
The Brucella abortus ribosomal protein L7/L12 is an immunodominant antigen and an interesting candidate for the development of oral live vaccines against brucellosis. Here, a recombinant Lactococcus lactis strain producing L7/L12 under the control of nisin inducible promoter was orally administered to BALB/c mice. Significant levels of anti-L7/L12 specific IgA detected in feces revealed an induced local humoral immune response. However, serum analysis did not reveal any anti-L7/L12 antibodies suggesting the absence of a systemic response. Nevertheless, the vaccinated mice showed a partial protective immunity against B. abortus virulent strain (S2308) challenged by intraperitoneal inoculation.  相似文献   
82.
Tissue lesion mechanisms provoked by sepsis include the infectious process, inflammation, and cellular energy deficit. We chose to test fructose-1,6-bisphosphate (FBP) because of its possible anti-inflammatory and antimicrobial actions. Wistar rats were used and divided into three experimental groups: a control group (n=10), in which a capsule was introduced into the peritoneum of the animals; a septic group (n=10), in which a capsule containing non-sterile fecal matter was introduced together with Escherichia coli (1.5 x 10(9)CFU); and a septic group treated with FBP 500 mg/kg (n=10). The blood cell tests revealed that levels of leukocytes increased significantly in the septic group when compared to both the septic group treated with FBP and the control group. The blood cultures were 100% positive in both the septic group and the septic group treated with bisphosphorylated sugar. The antibiogram only revealed an inhibitory halo in the case of the antibiotic ampicillin, there was no such indication for FBP. The anti-inflammatory power of FBP remained at 60% for 5 h in the rats that received the carrageenan injection. What is more, the sugar reduced the levels of ionic calcium in relation to the control group. This data proves the validity of using FBP in the treatment of sepsis, possibly due to its anti-inflammatory rather than antimicrobial action.  相似文献   
83.
84.
Skp2 protein expression in soft tissue sarcomas.   总被引:15,自引:0,他引:15  
BACKGROUND: p45 S phase kinase-associated protein-2 (p45(skp2)), a member of the F-box family of proteins, is an important component of the Skp1-Cullin-F-box protein (SCF) ubiquitin-ligase complex (SCF(skp2)). The latter has been implicated in the ubiquitination and degradation of p27(kip1) (p27) and G(1)-S cell cycle progression. The expression and prognostic role of Skp2 in a large series of soft tissue sarcomas has not been previously investigated. METHODS: Clinicopathologic features and immunohistochemical expression of Skp2, p27, and Ki-67 proteins were studied in 182 cases of soft tissue sarcomas (American Joint Committee on Cancer stages II and III). Survival analyses were performed using the Kaplan-Meier method and the Cox regression model. RESULTS: The male to female ratio was 1.2:1, and the median age at the diagnosis was 53 years. The tumors were predominantly located in the lower extremities (n = 163; 90%) and had a median size of 9 cm. High Skp2 expression (> or = 10% of the cells) was identified in 68 tumors (37%), and was correlated with high grade histology (P =.002) and Ki-67 proliferative index (r = 0.44; P <.0001), but not with p27 expression (r = -0.02; P =.80). By univariate analysis, high Skp2 expression was associated with decreased metastasis-free, disease-free, and overall survival. In a multivariate model, high Skp2 expression was an independent predictor for decreased local recurrence-free, disease-free, and overall survival. CONCLUSION: These results indicate that Skp2 expression is associated with cell proliferation and a worse prognosis in soft tissue sarcomas. The lack of an inverse correlation between Skp2 and p27 suggests that additional molecular events associated with either Skp2 expression or p27 proteolysis may be operating in these tumors.  相似文献   
85.
86.
Vergote IB, de Oliveira CF, Dargent D. How to organize gynecologic oncologyin the future: Results of an international questionnaire. Int J GynecolCancer 1997; 7: 368–375.
A questionnaire was sent to 93 gynecologic oncologists from 54 countriesabout the way in which gynecologic oncology was organized in their country, orif the (sub)speciality wasnot yet recognized, how they thought it should be organized. The questionnairewas answered by 64 persons from 42 different countries. The subspecialty wasrecognised in 17 (41%) of the countries. Fifty-five respondents (86%) thought thatgynecologic oncology should be a subspecialty of obstetrics and gynecology. Themedian duration of the gynecologiconcologic fellowship program was 30 months. Diagnosis and surgery accounted forabout 58% of the duration of the program. In 52% of the answersfrom countries with boardcertification, the fellows had to pass a theoretical and practical examination,and in addition 22% of the candidates had to defend a thesis to qualifyfor certification.Training centers in countries that recognized gynecologic oncology had amedian number of 142 new cases per year (for 1 fellow). The median number ofgynecologic oncologogistsand fellows per 10(7) inhabitants in countries with boardcertification in gynecologic oncology was 42 and 6, respectively. Finally, theimportant role of internationalsocieties (like the International Gynecologic Cancer Society and the EuropeanSociety of Gynaecological Oncology) in supporting the countries withoutrecognized GynecologicOncology was stressed by the respondents. The setting up of internationalstandards for training programs, training centers, board certification, and theorganization ofinternational exchange programs for fellows seemed to be equally important,according to the questionnaire responses.  相似文献   
87.
By using the Golgi technique, the authors investigated the morphology of ganglion cells in the retinas of South American opossums. In flat-mount preparations of the retinas, cell bodies, entire dendritic fields, and the stratification level of ganglion cells were studied. Fractal dimensions of dendritic trees, an objective quantitative measure of morphological complexity, were included as a morphological parameter of classification. Based on these characteristics, nineteen types of ganglion cells were described. A great number of opossum ganglion cell types had dendrites stratifying in both sublaminae of the inner plexiform layer (IPL) in five different ways (S1-S3 [G9], S1-S4 [G17 and G22], S2/S3 [G19], S2-S4 [G15, G16, G21 and G221, and S2-S5 [G61), and only two types (G8, and G10) showed narrow field dendritic trees ramifying in S4 only. Morphological types of opossum ganglion cells were compared to their counterparts in cat retina. The distribution pattern of large cell bodies on the ganglion cell layer was analyzed employing the Nissl staining method, immunocytochemistry for neurofilaments, and the reduced silver neurofibrillar staining method. The results showed a random pattern of distribution.  相似文献   
88.
89.
In the present study, we evaluated the effect of fructose-1,6-bisphosphate (FBP), a high energy intermediate metabolite of glycolysis, in an acute model of lung injury. Injection of carrageenan into the pleural cavity of rats elicited an acute inflammation response characterized by a fluid accumulation in the pleural cavity which contained a large number of polymorphonuclear neutrophils. FBP (500mg/kg) attenuated the inflammation parameters: exudate volume, total leukocytes and the number of polymorphonuclear leukocytes, but the protein concentration in the exudate was not significantly affected by treatment with FBP. The precise site and mechanism of the anti-inflammatory effect was not addressed, considering the diverse pharmacological actions of FBP. This drug has anti-inflammatory actions suggesting that it may represent a novel strategy for the modulation of inflammatory response.  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号