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   119956篇
  免费   10296篇
  国内免费   9774篇
  140026篇
  2024年   766篇
  2023年   1621篇
  2022年   3614篇
  2021年   5984篇
  2020年   4280篇
  2019年   5149篇
  2018年   4871篇
  2017年   3606篇
  2016年   5089篇
  2015年   7382篇
  2014年   8724篇
  2013年   9198篇
  2012年   11049篇
  2011年   9975篇
  2010年   6225篇
  2009年   5558篇
  2008年   6337篇
  2007年   5703篇
  2006年   5025篇
  2005年   3970篇
  2004年   3389篇
  2003年   3163篇
  2002年   2625篇
  2001年   2088篇
  2000年   1885篇
  1999年   1848篇
  1998年   1149篇
  1997年   1094篇
  1996年   1040篇
  1995年   920篇
  1994年   866篇
  1993年   665篇
  1992年   884篇
  1991年   674篇
  1990年   519篇
  1989年   481篇
  1988年   380篇
  1987年   362篇
  1986年   294篇
  1985年   309篇
  1984年   170篇
  1983年   167篇
  1982年   107篇
  1981年   90篇
  1980年   63篇
  1979年   79篇
  1977年   60篇
  1975年   56篇
  1974年   52篇
  1973年   57篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
161.
The study's objective is to survey the attitudes of Chinese people living in Hong Kong toward genomic science and technology (GST) and their ethical and social implications. Using a 24-item questionnaire, 877 Cantonese-speaking residents between age 18 and 64 with minimum high school education are interviewed by telephone. Multiple regression analysis identifies education level as the most important demographic variable. Overall, respondents have mild agreement with genetic determinism and the use of GST for disease prevention but not for non-therapeutic genetic enhancement and production of “genetically modified” crops or meat. Respondents strongly believe that GST tampers with nature and resources should be used to solve other healthcare problems first. Respondents also show little concern that personal genetic information may be abused by their employers or schools and have only a minimal willingness to share personal genetic information with their family members.  相似文献   
162.
The podocyte is a remarkable cell type, which encases the capillaries of the kidney glomerulus. Podocytes are of keen interests because of their key roles in kidney development and disease. Large-conductance Ca2+-activated K+ channels (BKCa channels) are important ion channels located in podocytes and play the essential role in regulating calcium homeostasis cell signaling. In this research, we studied the undergoing developmental changes of BKCa channels and their contribution to functional maturation of podocytes. Our results showed that the distribution of BKCa channels changed with the maturity of differentiation in a conditionally immortalized mouse podocyte cell line. Additionally, the increase of BKCa channel protein expression was detected by immunofluorescence staining with confocal microscopy in podocytes, which was consistent with the increase in the current density of BKCa channels examined by whole-cell patch-clamp technique. Our results suggested that the developmental changes of BKCa channels may help podocytes adapt to changes in pressure gradients occurring in physiological conditions. Those findings may have implications for understanding the physiology and development of kidney and will also serve as a baseline for future studies designed to investigate developmental changes of ion channel expression in podocytes.  相似文献   
163.
The explosive Koi herpesvirus (KHV) epidemic has caused the deaths of a large number of carp and carp variants and has produced serious economic losses. The mirror carp (Cyprinus carpio var. specularis) exhibits strong environmental adaptability and its primary cells can be used to isolate KHV. This study utilized the tissue explant method to systematically investigate primary cell culture conditions for mirror carp snout and caudal fin tissues. We demonstrated that cells from these two tissue types had strong adaptability, and when cultured in Medium 199 (M199) containing 20% serum at 26 to 30°C, the cells from the snout and caudal fin tissues exhibited the fastest egress and proliferation. Inoculation of these two cell types with KHV-infected fish kidney tissues produced typical cytopathic effects; additionally, identification by electron microscopy, and PCR indicated that KHV could be isolated from both cell types.  相似文献   
164.
Cloud computing provides many kinds of application services for cloud users, but security problems have caused great impact on Software as a Service (SaaS). As a commercial model, SaaS is related among different participants who could be malicious or dishonest. This paper presents a Software Service Signature (S3) to deal with several security issues in SaaS and keep the interests and rights of all participants in safety. Our design is based on ID-based proxy signatures from pairings. The analysis shows that the proposed scheme can effectively strengthen the security through authentication in cloud computing.  相似文献   
165.
166.
The aim of malignant glioma treatment is to inhibit tumor cell proliferation and induce tumor cell apoptosis. Remifentanil is a clinical anesthetic drug that can activate the N-methyl-D-aspartate (NMDA) receptor. NMDA receptor signaling activates glycogen synthase kinase-3β (GSK-3β). Discovered some 32 years ago, GSK-3β was only recently considered as a therapeutic target in cancer treatment. The purpose of this study was to assess whether remifentanil can induce the apoptosis of C6 cells through GSK-3β activation. 3-(4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) was used to detect cell viability. Hoechst 33342 staining and flow cytometry were used to detect cell apoptosis. The effect of GSK-3β activation was detected using a GSK-3β activation assay kit and 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), a potent and selective small molecule inhibitor of GSK-3β. The MTT assay indicated that remifentanil induced C6 cell death in a concentration- and time-dependent manner. Hoechst 33342 staining and flow cytometry showed that remifentanil significantly induced C6 cell apoptosis. The measurement of GSK-3β activation showed that remifentanil increased the cellular level of GSK-3β. All of these toxic effects can be attenuated by treatment with TDZD-8. These results suggest that remifentanil is able to induce C6 cell apoptosis through GSK-3β activation, which provides a basis for its potential use in the treatment of malignant gliomas.  相似文献   
167.
The residues of organochlorine pesticides (OCPs) in surface waters from Meiliang Bay, Gonghu Bay, and Xukou Bay of Lake Taihu, China, were investigated, and their ecological risks were assessed using the risk quotient method and probabilistic risk assessment. Environmental concentrations of OCPs in surface water of these bays were relatively lower compared with other rivers or lakes in China. Calculation of risk quotient associated with taxonomic groups indicates moderate ecological risks from OCPs for crustaceans and insects in these bays, while the ecological risks were low for fish and negligible for phytoplankton. The ecological risk quotients associated with individual OCPs were lower than 0.01 in these bays, suggesting a negligible risk to aquatic organisms. Ecological risk from α-HCH was relatively lower compared with DDTs, endosulfans, and γ-HCH. The combined ecological risks were evaluated using probabilistic risk assessment for only eight OCPs owing to a lack of available toxicity data for β-HCH and δ-HCH. The percentage of species with the potential to be at risk from mixture of OCPs was lower than the criteria of 5% in each bay, indicating that the combined ecological risks were acceptable.  相似文献   
168.
169.
Abstract

Background: Platinum compounds are commonly used for lung cancer treatment. However, the severe side effects and relatively poor prognosis limit their therapeutic effect. Therefore, developing novel platinum derivative and treatment strategy are critical for current lung cancer therapy.

Methods: Flow cytometry, HMGB1 and ATP release, and immunoblotting were performed to evaluate the Oxaliplatin-induced immunogenic cell death (ICD) in two lung carcinoma cells. Vaccination approach and subcutaneous tumor models were created to analyze the tumor regression effect of Oxaliplatin. PD-L1 mRNA and protein levels were detected in LLC (Lewis lung carcinoma). Enhanced therapeutic efficacy of LLC was assessed by co-administration Oxaliplatin and aPD-L1 in murine lung tumor model.

Results: Oxaliplatin induced robust ICD in LLC cells, activated dendritic cells (DCs, CD80+CD86+) and enhanced cytotoxic T cells (CD8+) in LLC tumor tissues, which resulted in tumor regression. Co-administration of Oxaliplatin and checkpoint inhibitor, aPD-L1, could enhance the therapeutic efficacy of LLC in murine lung carcinoma.

Conclusion: This study reveals Oxaliplatin can induce robust ICD in tumor tissues and suppress tumor growth by activating DCs and enhancing T-cell infiltration. Notably, the Oxaliplatin-induced ICD provides an immunogenic microenvironment, which enhances the checkpoint inhibitor therapeutic efficacy of LLC.  相似文献   
170.
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