全文获取类型
收费全文 | 197285篇 |
免费 | 2086篇 |
国内免费 | 170篇 |
专业分类
耳鼻咽喉 | 1380篇 |
儿科学 | 7079篇 |
妇产科学 | 3150篇 |
基础医学 | 19397篇 |
口腔科学 | 1999篇 |
临床医学 | 13882篇 |
内科学 | 36285篇 |
皮肤病学 | 1240篇 |
神经病学 | 18107篇 |
特种医学 | 9725篇 |
外国民族医学 | 1篇 |
外科学 | 32303篇 |
综合类 | 2384篇 |
一般理论 | 5篇 |
预防医学 | 18531篇 |
眼科学 | 3561篇 |
药学 | 11000篇 |
中国医学 | 675篇 |
肿瘤学 | 18837篇 |
出版年
2023年 | 124篇 |
2022年 | 238篇 |
2021年 | 571篇 |
2020年 | 304篇 |
2019年 | 389篇 |
2018年 | 22335篇 |
2017年 | 17658篇 |
2016年 | 19900篇 |
2015年 | 1426篇 |
2014年 | 1454篇 |
2013年 | 1530篇 |
2012年 | 8226篇 |
2011年 | 22269篇 |
2010年 | 19570篇 |
2009年 | 12124篇 |
2008年 | 20629篇 |
2007年 | 22929篇 |
2006年 | 1834篇 |
2005年 | 3556篇 |
2004年 | 4774篇 |
2003年 | 5579篇 |
2002年 | 3791篇 |
2001年 | 728篇 |
2000年 | 800篇 |
1999年 | 609篇 |
1998年 | 566篇 |
1997年 | 469篇 |
1996年 | 364篇 |
1995年 | 337篇 |
1994年 | 314篇 |
1993年 | 278篇 |
1992年 | 304篇 |
1991年 | 324篇 |
1990年 | 385篇 |
1989年 | 316篇 |
1988年 | 265篇 |
1987年 | 190篇 |
1986年 | 169篇 |
1985年 | 205篇 |
1984年 | 151篇 |
1983年 | 124篇 |
1982年 | 103篇 |
1981年 | 75篇 |
1980年 | 109篇 |
1979年 | 100篇 |
1978年 | 90篇 |
1974年 | 57篇 |
1970年 | 62篇 |
1969年 | 63篇 |
1938年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Shiro Akinaga Tadashi Ashizawa Katsushige Gomi Hiroe Ohno Makoto Morimoto Chikara Murakata Masami Okabe 《Cancer chemotherapy and pharmacology》1992,29(4):266-272
Summary Novel derivatives of K-252a, (8R*,9S*,11S*)-(–)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9,10-tetrahydro-8, 11-epoxy-1H,8H,11H-2,7b,11a-triazadibenzo [a,g]-cycloocta[cde]trinden-1-one, an inhibitor of protein kinases and calmodulin-dependent phosphodiesterase, were synthesized and evaluated for their antitumor activity in vitro and in vivo. Of ten derivatives tested, four were active against the P388 murine leukemia i. p.-i. p. system, although K-252a was inactive. Among these derivatives, KT6124 was selected for further biological evaluation studies because its efficacy was the highest. KT6124 was also active against sarcoma 180 and B16 melanoma. It exerted a relatively broad spectrum of antiproliferative activity against 20 human tumor cell lines in vitro. To determine the mechanism(s) of action underlying the antitumor activity of KT6124, we tested the drug for inhibition of protein kinases, including Ca2+-and phospholipid-dependent protein kinase (PKC), in intact A431 human epidermoid carcinoma cells in comparison with the PKC-inhibitory activity of K-252a. KT6124 did not antagonize the action of phorbol 12-myristate 13-acetate (PMA) in A431 cells, whereas K-252a did, suggesting that KT6124 may not act on protein kinases in the cells. The interaction of KT6124 with DNA in living cells was examined by the alkaline elution method. KT6124 apparantly exhibited DNA scission both dose-and time-dependently in the target cells. The DNA breakage was dependent on proteinase K treatment, suggesting its possible interaction with DNA-related enzyme(s). These results indicate that KT6124 exerts antitumor activity by acting on DNA or on DNA-related enzyme(s) in tumor cells rather than via the inhibition of protein kinases. 相似文献
42.
Hironobu Ishiyama Makoto Sato Kuniko Matsumura Miwa Sento Keiki Ogino Tatsuya Hobara 《Basic & clinical pharmacology & toxicology》1995,77(4):293-298
Abstract: Intravenous injection of gadolinium chloride (GdCl3) at a dose of 10 mg/kg caused an increase in proliferating cell nuclear antigen labeling index and the grade of pyronin positivity (RNA level) in rat liver. In CCl4-exposed rats, pretreatment with GdCl3 also showed a preventive effect of the liver injury both biochemically and histologically. Moreover, the proliferative action preceded the attenuative effect of the liver injury. Results suggest that GdCl3 induces hepatocyte proliferation, and this action of GdCl3 may modify the development of CCl4-induced liver injury. 相似文献
43.
Irwin L. Flink 《Brain structure & function》2002,205(3):235-244
44.
Kentaro Yamasaki Takafumi Ishida Tatsuya Kishino Norio Niikawa 《American journal of medical genetics. Part A》2002,111(3):301-306
We report on a Thai family with dominantly inherited malformation syndrome with upper limb anomalies, short stature, quadricuspid aortic valve, and minor craniofacial anomalies. The affected individuals comprised a mildly affected mother, a moderately affected daughter, and a most severely affected son. The daughter and son had short stature. The craniofacial abnormalities comprised frontal bossing, hypoplastic nasal bones, depressed nasal bridge, and broad nasal alae. The upper limb defects varies among the patients, ranging from radial ray defects in the mother through radial and ulnar ray defects with unilateral humeral hypoplasia in the daughter to radial ray defects with severe oligodactyly and bilateral humeral hypoplasia in the son. All patients in this family had hypoplasia of the shoulder girdle and resembled what is observed in many families with Holt‐Oram syndrome. Moreover, the son showed quadricuspid aortic valve with mild aortic regurgitation. However, the present family did not show any mutation of the TBX5 gene, a disease‐causing gene of Holt‐Oram syndrome. The present family deserves further investigation on other genes that play a role in the development of the upper limbs, particularly of radial rays. © 2002 Wiley‐Liss, Inc. 相似文献
45.
46.
47.
48.
Paul Hochstein Ulrich Glatzel Thomas Schmickal Andreas Wentzensen 《Trauma und Berufskrankheit》2002,4(2):s110-s114
The treatment of deep cartilage defects in load-bearing joints is a problem that still has no satisfactory solution. Full-thickness defects of the articular cartilage rarely heal spontaneously, usually leaving damage that can lead to early arthrosis. Techniques currently available for the treatment of chondral defects include abrasion, drilling, micro-fracturing, transplantation of tissue autografts and allografts, and cell transplantation. Osteochondral autograft transplantation is currently the only surgical cartilage repair technique known to lead to the formation of genuine hyaline articular cartilage and its retention at least in the medium term. The Draenert method, in which a water-cooled diamond bone-cutting system is used, is an effective procedure for resurfacing the joints affected by localised cartilaginous defects, even when there is also severe bone loss. Donor-side morbidity can be kept to a minimum by filling the defect caused by harvesting with a press-fit cylinder of cancellous bone covered with periosteum for protection. 相似文献
49.
Annemieke Smit-van Oosten Winston W. Bakker Harry van Goor 《Transplant international》2002,15(12):602-609
Ischemic injury plays an important role in chronic renal transplant failure (CRTF). Down-regulation of ecto-adenosine triphosphatase (ATPase) in combination with up-regulation of ecto-5'-nucleotidase is a hallmark of ischemic injury. We studied the expression of renal ecto-5'-nucleotidase and ecto-ATPase in experimental renal transplantation. Fisher 344-to-Lewis allografted rats were either treated with an angiotensin-converting enzyme inhibitor (ACEi) or left untreated. Lewis-to-Lewis syngrafted rats served as controls. Untreated allografted rats developed proteinuria, glomerulosclerosis, and mild intimal hyperplasia. ACEi completely prevented focal and segmental glomerulosclerosis (FGS) and proteinuria, but significantly enhanced intimal hyperplasia. Untreated allografted rats revealed marked vascular ecto-5'-nucleotidase activity, which increased with ACEi. Vascular ecto-5'-nucleotidase activity was absent in syngrafted animals. Ecto-5'-nucleotidase activity correlated well with intimal hyperplasia. Glomerular ecto-ATPase expression was significantly reduced in untreated allografted rats compared to syngrafted rats and correlated well with the extent of FGS. ACEi prevented reduction in glomerular ecto-ATPase. We found de-novo expression of ecto-5'-nucleotidase at sites of renal intimal hyperplasia. Glomerular ecto-ATPase expression was markedly reduced in allografted rats and was prevented by ACEi. These enzyme expression patterns suggest local ischemic damage in experimental CRTF. 相似文献
50.
J. Bryan Page 《Journal of urban health》2005,82(3):iii35-iii43
Contemporary discourse contains numerous examples of use of the concept of culture by social and behavioral scientists. Simple reification, where the speaker makes culture into a thing capable of action exemplifies one usage in public discourse. Some quantitative social scientists attempt to characterize people’s cultural identities by means of a single categorical variable, which often “lumps” people into categories such as “Hispanic” or “Black” that in fact have numerous culturally bounded subcategories. Approaches that emphasize cultural process are preferable to those who attempt to categorize; more complex measures of acculturation help investigators to make convincing analyses of circumstances in which health disparities occur. Examples in which investigators make appropriate use of cultural characterizations demonstrate their utility in investigating health disparities in Haitian American women, injecting and noninjecting drug users, Hispanic youth, and adult Hispanics at risk of HIV infection. Focus on culture in the study of health disparities can identify entanglements between structural factors such as poverty and lack of education and cultural factors such as beliefs about health. Qualitative methods coupled with quantitative methods have great potential to improve investigators’ grasp of cultural nuance while capturing the distribution of qualitatively derived behaviors. 相似文献