全文获取类型
收费全文 | 2937632篇 |
免费 | 233444篇 |
国内免费 | 5876篇 |
专业分类
耳鼻咽喉 | 42595篇 |
儿科学 | 91339篇 |
妇产科学 | 80703篇 |
基础医学 | 413718篇 |
口腔科学 | 84000篇 |
临床医学 | 263803篇 |
内科学 | 576204篇 |
皮肤病学 | 60426篇 |
神经病学 | 245268篇 |
特种医学 | 117849篇 |
外国民族医学 | 1130篇 |
外科学 | 449191篇 |
综合类 | 68512篇 |
现状与发展 | 1篇 |
一般理论 | 1170篇 |
预防医学 | 233108篇 |
眼科学 | 69244篇 |
药学 | 218492篇 |
4篇 | |
中国医学 | 5551篇 |
肿瘤学 | 154644篇 |
出版年
2018年 | 30021篇 |
2016年 | 25540篇 |
2015年 | 28875篇 |
2014年 | 41594篇 |
2013年 | 63570篇 |
2012年 | 85631篇 |
2011年 | 90453篇 |
2010年 | 53652篇 |
2009年 | 51493篇 |
2008年 | 86130篇 |
2007年 | 91486篇 |
2006年 | 92330篇 |
2005年 | 90155篇 |
2004年 | 86651篇 |
2003年 | 83803篇 |
2002年 | 82605篇 |
2001年 | 135256篇 |
2000年 | 139601篇 |
1999年 | 118266篇 |
1998年 | 34110篇 |
1997年 | 31070篇 |
1996年 | 30847篇 |
1995年 | 29621篇 |
1994年 | 27829篇 |
1993年 | 26045篇 |
1992年 | 94854篇 |
1991年 | 91524篇 |
1990年 | 88546篇 |
1989年 | 85341篇 |
1988年 | 79370篇 |
1987年 | 78132篇 |
1986年 | 74352篇 |
1985年 | 70867篇 |
1984年 | 53589篇 |
1983年 | 45733篇 |
1982年 | 27944篇 |
1981年 | 24732篇 |
1980年 | 23302篇 |
1979年 | 50231篇 |
1978年 | 35157篇 |
1977年 | 29742篇 |
1976年 | 27934篇 |
1975年 | 29707篇 |
1974年 | 36402篇 |
1973年 | 34651篇 |
1972年 | 32581篇 |
1971年 | 30110篇 |
1970年 | 28472篇 |
1969年 | 26572篇 |
1968年 | 24493篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
991.
B A Thornhill H T Morehouse J C Hoffman-Tretin 《Critical reviews in diagnostic imaging》1988,28(1):1-22
Computed tomography (CT) is currently the imaging modality of choice for assessing the morphology of the adrenal glands in adult patients. Much useful information can be gained using CT in disease processes which primarily involve one or both of the adrenal glands, such as adenomas, as well as in entities which secondarily affect the adrenals, such as pituitary or metastatic disease. The size and configuration of the glands can be readily determined, and masses may be detected. We discuss CT of normal and abnormal adrenal glands with sonographic (US) and pathological correlation, when available. Entities which may mimic adrenal abnormalities are emphasized. Relative advantages of US over CT in the pediatric patient are discussed. 相似文献
992.
The impact of recombinant human tumour necrosis factor-alpha (1 microgram kg-1 to 1 mg kg-1; 6.6 x 10(6) U mg protein-1) on blood flow, oxygen consumption and growth of a moderately TNF-sensitive rat tumour (DS-carcinosarcoma) was studied. Tumour growth was stimulated at low TNF doses (1 and 10 micrograms kg-1) and significantly retarded at higher TNF dose levels (0.1 and 1 mg kg-1). Growth changes were concomitant with variations in oxygen consumption, lactate release and acidification of the metabolic micromilieu. Both single and repeated application of low TNF doses (1-10 micrograms kg-1 i.v.) increased tumour perfusion whereas single administration of high TNF dose levels (0.1-1 mg kg-1 i.v.) reduced tumour blood flow. After repeated application of high TNF doses tumours shrank to such small sizes that perfusion measurements could not be performed within the observation period of two weeks. It is concluded that TNF effects on solid tumours are at least partially mediated by changes in tumour perfusion. Thus, an altered tumour sensitivity towards other treatment modalities, e.g. irradiation, chemotherapy or hyperthermia, can be expected after TNF therapy. A beneficial TNF effect would critically depend on the dose level employed and on the sequence and timing of various combination regimes. 相似文献
993.
994.
995.
996.
Excretory/secretory antigen of Toxocara canis: recognition profiles of polyclonal and larvicidal monoclonal antibodies 总被引:1,自引:1,他引:0
Summary Five monoclonal antibodies against the excretory/secretory (E/S) antigen of Toxocara canis were obtained and characterized. Immunoprecipitating activity was demonstrated in an in-vitro micropre-cipitating assay using live T. canis larvae. Their capacity to kill larvae was also shown in an in-vitro assay. Two zones of reactivity were observed in 7.5 and 12.5% SDS-PAGE (177-77 kD, 43-15 kD) of immunoprecipitates of human and mouse positive polyclonal anlisera. The murine monoclonal antibodies showed a common pattern of reactivity with the proteins in the 177-77 kD range. 相似文献
997.
Tissue-specific regulation of pyroglutamate aminopeptidase II activity by thyroid hormones 总被引:2,自引:0,他引:2
Among the enzymes capable of degrading thyrotropin-releasing hormone (TRH) in vitro, two pyroglutamate aminopeptidases (PGA) are specific for TRH: thyroliberinase, a seric enzyme and PGAII, a membrane-bound peptidase. The effect of thyroid hormone status on the activity of these enzymes was evaluated in serum and various tissues. Only in adenohypophysis, triiodothyronine treatment increased PGAII to 376% of control; hypothyroidism produced the reverse effect (decrease to 23% of control). As previously reported, similar changes were observed for thyroliberinase. TRH degradation at the adenohypophysis level may participate in the negative feedback control of thyroid hormones. 相似文献
998.
R Rosso F Boccardo F Brema M R Sertoli D Amoroso G Bertelli P Pronzato 《Anticancer research》1989,9(4):1153-1156
131 patients with resectable, node-positive breast cancer were treated at the National Institute for Cancer Research of Genoa, Italy with a systemic adjuvant regimen based on 14 cycles of chemotherapy, immunostimulation with levamisole, and--for postmenopausal patients--hormone therapy with tamoxifen. The present evaluation is performed eleven years after the admission of the first patient: so far, 75 patients (57.3%) have relapsed and 52 (39.7%) have died. An analysis of prognostic factors for relapse and death shows that the number of positive axillary lymph nodes and the dimension of the primary tumor are significantly associated with survival and relapse-free survival, while age and menopausal status are not. 相似文献
999.
1000.
B. Ehlers E. Strauch M. Goltz D. Kubsch H. Wagner H. Maidhof J. Bendiek B. Appel H. -J. Buhk 《Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz》1997,40(4):118-121
Zusammenfassung Ein PCR-Nachweis für gentechnisch ver?nderten Mais ?Event 176? der Fa. Ciba-Geigy wurde etabliert. Der Mais enth?lt Gene,
die Selbstschutz gegen den Maiszünsler (Delta-Endotoxin-Gen ausBacillus thuringiensis) und Toleranz gegen das Herbizid Basta (Phosphinothricin-Resistenz-Gen ausStreptomyces hygroscopicus) vermitteln. Zudem enth?lt der Mais ein Ampicillin-Resistenz-Gen. Für die Amplifikation von Bereichen aus allen drei Genen
wurden PCR-Primer entworfen. Mit Hilfe dieser Primer und mit ?Event 176?-Mais-DNA als Template konnten die entsprechenden
Genbereiche in der PCR amplifiziert werden. Die PCR-Produkte wurden sequenziert, um ihre Identit?t zu best?tigen. Mit Hilfe
der Delta-Endotoxin-PCR wurden, auch in Gegenwart von 104fachem überschu? nicht gentechnisch ver?nderter Mais-DNA, fünf haploide Genome der ?Event 176?-DNA nachgewiesen.
Identification of genetically modified maize by PCR
Summary A PCR-test for the genetically modified maize ?Event 176? of Ciba-Geigy was established. The maize contains genes conferring resistance to the European corn borer (delta-endotoxin gene fromBacillus thuringiensis) and tolerance to the herbicide Basta (phosphinothricin resistance gene fromStreptomyces hygroscopicus). The maize contains also an ampicillin resistance gene. Primers were designed and using ?Event 176?-maize-DNA as template internal regions of the three genes were amplified with PCR. The PCR products were sequenced to confirm their identity. Using the deltaendotoxin primers in PCR down to 5 haploid genomes of ?Event 176?-DNA could be detected, even in the presence of a 104fold excess of DNA from non-modified maize.相似文献