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   12952篇
  免费   641篇
  国内免费   32篇
耳鼻咽喉   171篇
儿科学   377篇
妇产科学   352篇
基础医学   1616篇
口腔科学   304篇
临床医学   758篇
内科学   3510篇
皮肤病学   407篇
神经病学   859篇
特种医学   198篇
外科学   1709篇
综合类   133篇
一般理论   2篇
预防医学   1394篇
眼科学   232篇
药学   887篇
中国医学   79篇
肿瘤学   637篇
  2023年   87篇
  2022年   91篇
  2021年   282篇
  2020年   150篇
  2019年   342篇
  2018年   509篇
  2017年   289篇
  2016年   304篇
  2015年   283篇
  2014年   368篇
  2013年   534篇
  2012年   880篇
  2011年   942篇
  2010年   508篇
  2009年   360篇
  2008年   788篇
  2007年   818篇
  2006年   852篇
  2005年   806篇
  2004年   737篇
  2003年   712篇
  2002年   655篇
  2001年   379篇
  2000年   457篇
  1999年   328篇
  1998年   72篇
  1997年   55篇
  1996年   41篇
  1995年   29篇
  1994年   33篇
  1993年   34篇
  1992年   104篇
  1991年   88篇
  1990年   102篇
  1989年   70篇
  1988年   59篇
  1987年   63篇
  1986年   62篇
  1985年   46篇
  1984年   24篇
  1983年   28篇
  1982年   17篇
  1980年   14篇
  1979年   14篇
  1978年   18篇
  1976年   14篇
  1974年   14篇
  1973年   16篇
  1971年   20篇
  1969年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
FGFR3 and Tp53 mutations have been proposed as defining two alternative pathways in the pathogenesis of transitional bladder cancer. FGFR3 mutations are associated with low-grade tumors and a favorable prognosis. Tp53 alterations are associated with advanced tumors and, possibly, with a poor prognosis. We focus here on the subgroup of T1G3 superficial tumors because they are a major clinical challenge. Patients (n = 119) were identified from a prospective study of 1,356 cases. Mutations in FGFR3 (exons 7, 10, and 15) and Tp53 (exons 4-9) were analyzed using PCR and direct sequencing. All cases were followed for recurrence and death. Survival was analyzed using Kaplan-Meier curves and multivariable Cox regression. FGFR3 mutations were detected in 20 (16.8%) tumors; 100 mutations in Tp53 were found in tumors from 78 (65.5%) cases. Multiple alterations in Tp53 were present in 19 tumors (16%). Inactivating mutations were present in 58% of tumors. The combined mutation distribution (FGFR3/Tp53) was: wt/wt (34.5%), mut/wt (7.6%), wt/mut (48.7%), and mut/mut (9.2%), indicating that the presence of either mutation did not depend on the other (P value = 0.767). FGFR3 and Tp53 mutations were not associated with clinicopathologic characteristics of patients and did not predict, alone or in combination, recurrence or survival. Taking the risk of the wt/wt group as reference, the mutation-associated risks of cancer-specific mortality were: mut/wt 1.42 (0.15-13.75), wt/mut 0.67 (0.19-2.31), mut/mut 1.62 (0.27-9.59). These molecular features support the notion that T1G3 tumors are at the crossroads of the two main molecular pathways proposed for bladder cancer development and progression.  相似文献   
153.
154.
155.
In the approach to lipid-related risk factors for cardiovascular diseases, serum high density lipoprotein-cholesterol (HDL-C) levels bear a particular significance as this lipoprotein is considered to be an antiatherogenic factor mainly, but not only, because of its influence and impact on reverse cholesterol transport. Hence the need and requirement to consider serum HDL-C levels for both primary and secondary prevention of cardiovascular disease. A particularly important aspect is the association of the 'low HDL syndrome' with the metabolic syndrome. These factors force us to consider serum HDL-C level as a therapeutic target by itself, or even in association with low density lipoprotein-cholesterol (LDL-C) levels when the latter are increased. This review stresses the aspects connecting serum HDL-C levels and cardiovascular risk, and looks at the populations that should be considered amenable to therapeutic management because of low serum HDL-C levels. We review therapeutic strategies, both pharmacological and nonpharmacological. The aim of this review is to present therapeutic management recommendations for correcting the proportion of cardiovascular risk that is attributable to changes in HDL-C. Serum HDL-C levels of >40 mg/dL must be a therapeutic target in primary and secondary prevention. This goal is particularly important in patients with low serum HDL-C levels and ischemic heart disease (IHD) or its equivalents, even if the therapeutic target for serum LDL-C levels (<100 mg/dL) has been achieved. The first choice for this clinical condition is fibric acid derivates. The same therapeutic option should be considered in patients without IHD with low serum HDL-C levels and high cardiovascular risk (>20%), hypertriglyceridemia, type 2 diabetes mellitus, or metabolic syndrome.  相似文献   
156.
Sporothrix schenckii is one of the causative agents of the deep-seated mycosis sporotrichosis, a fungal infection with worldwide distribution. Fungus-specific molecules and biosynthetic pathways are potential targets for the development of new antifungal drugs. The MNT1/KRE2 gene family is a group of genes that encode fungus-specific Golgi-resident mannosyltransferases that participate in the synthesis of O-linked and N-linked glycans. While this family is composed of five and nine members in Candida albicans and Saccharomyces cerevisiae, respectively, the S. schenckii genome contains only three putative members. MNT1 has been previously characterized as an enzyme that participates in the synthesis of both N-linked and O-linked glycans. Here, we aimed to establish the functional role of the two remaining family members, KTR4 and KTR5, in the protein glycosylation pathways by using heterologous complementation in C. albicans mutants lacking genes of the MNT1/KRE2 family. The two S. schenckii genes restored defects in the elaboration of N-linked glycans, but no complementation of mutants that synthesize truncated O-linked glycans was observed. Therefore, our results suggest that MNT1 is the sole member with a role in O-linked glycan elaboration, whereas the three family members have redundant activity in the S. schenckii N-linked glycan synthesis.  相似文献   
157.
158.
In the present study, we evaluated the effect of an albendazole (ABZ) derivative JVG9 on cultured Giardia intestinalis. To assess the JVG9 effects, we evaluated the tubulin cytoskeleton by confocal microscopy, and we found that the characteristic staining was modified. The scanning electron microscopy images revealed extremely damaged trophozoites and cyst-like cells. The confocal images revealed that this drug triggered the expression of cyst wall protein 1 and encystation. We also found that at low doses, AL triggered the encystation process too.  相似文献   
159.
Eight outbreaks of acute and subacute fasciolosis are reported in sheep in the municipality of Santa Vitória do Palmar, southern Brazil, in areas used for irrigated rice cultivation, which are subject to frequent flooding. Two outbreaks occurred mid-winter during July and August, and six occurred during spring and early summer. Morbidity ranged from 3 to 66.7 %, and mortality ranged from 3 to 50 %. Clinical signs included weight loss, mucosal pallor, apathy, depression, muscle tremors, and drooling; these were followed by death within approximately 24 h. Some sheep were found dead. Gross lesions were characterized by an irregular liver capsule with fibrin deposition and hemorrhages. The liver parenchyma contained hemorrhagic tracts or irregular clear areas alternated with dark hemorrhagic areas. Histologically, hemorrhagic dark red tracts of necrotic liver parenchyma and an inflammatory infiltrate were noted; these lesions coincided with the presence of immature flukes. Langhans-type giant cells, fibrous tissue, and bile duct cell proliferation were observed in subacute cases. Chronic fasciolosis is a well-known disease to farmers in southern Brazil; nevertheless, acute and subacute fasciolosis, which are more difficult to diagnose and treat, may cause important economic losses. Efficient control of fasciolosis requires integration of measures to treat infections in the definitive host, to reduce the population of snails of the genus Lymnaea, and to avoid contact between the parasite and host by appropriate pasture management.  相似文献   
160.
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