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   2120篇
  免费   166篇
  国内免费   6篇
耳鼻咽喉   8篇
儿科学   58篇
妇产科学   54篇
基础医学   338篇
口腔科学   21篇
临床医学   230篇
内科学   426篇
皮肤病学   54篇
神经病学   200篇
特种医学   48篇
外科学   153篇
综合类   12篇
一般理论   2篇
预防医学   253篇
眼科学   22篇
药学   241篇
中国医学   2篇
肿瘤学   170篇
  2023年   27篇
  2022年   54篇
  2021年   110篇
  2020年   69篇
  2019年   76篇
  2018年   92篇
  2017年   68篇
  2016年   62篇
  2015年   82篇
  2014年   89篇
  2013年   143篇
  2012年   188篇
  2011年   198篇
  2010年   96篇
  2009年   84篇
  2008年   105篇
  2007年   111篇
  2006年   119篇
  2005年   110篇
  2004年   94篇
  2003年   89篇
  2002年   61篇
  2001年   15篇
  2000年   6篇
  1999年   8篇
  1998年   13篇
  1997年   5篇
  1996年   5篇
  1995年   10篇
  1994年   3篇
  1992年   6篇
  1991年   10篇
  1990年   6篇
  1989年   3篇
  1987年   4篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   5篇
  1982年   3篇
  1981年   4篇
  1978年   5篇
  1971年   3篇
  1959年   2篇
  1954年   3篇
  1932年   2篇
  1930年   2篇
  1929年   2篇
  1927年   2篇
  1921年   2篇
排序方式: 共有2292条查询结果,搜索用时 31 毫秒
71.
72.
Respiratory depression has been attributed to buprenorphine (BUP) misuse or combination with benzodiazepines. BUP/naloxone (NLX) has been marketed as maintenance treatment, aiming at preventing opiate addicts from self-injecting crushed pills. However, to date, BUP/NLX benefits in comparison to BUP alone remain debated. We investigated the plethysmography effects of BUP/NLX in comparison to BUP/solvent administered by intravenous route in naive and BUP-tolerant Sprague-Dawley rats, and in combination with diazepam (DZP) or its solvent. In naive rats, BUP/NLX in comparison to BUP significantly increased respiratory frequency (f, P < 0.05) without altering minute volume (VE). In combination to DZP, BUP/NLX significantly increased expiratory time (P < 0.01) and decreased f (P < 0.01), tidal volume (VT, P < 0.001), and VE (P < 0.001) while BUP only decreased VT (P < 0.5). In BUP-tolerant rats, no significant differences in respiratory effects were observed between BUP/NLX and BUP. In contrast, in combination to DZP, BUP/NLX did not significantly alter the plethysmography parameters, while BUP increased inspiratory time (P < 0.001) and decreased f (P < 0.01) and VE (P < 0.001). In conclusion, differences in respiratory effects between BUP/NLX and BUP are only significant in combination with DZP, with increased depression in naive rats but reduced depression in BUP-tolerant rats. However, BUP/NLX benefits in humans remain to be determined.  相似文献   
73.
Ginkgolic acids and urushiols are natural alkylphenols known for their mutagenic, carcinogenic and genotoxic potential. However, the mechanism of toxicity of these compounds has not been thoroughly elucidated so far. Considering that the SIRT inhibitory potential of anacardic acids has been hypothesized by in silico techniques, we herein demonstrated through both in vitro and computational methods that structurally related compounds such as ginkgolic acids and urushiols are able to modulate SIRT activity. Moreover, their SIRT inhibitory profile and cytotoxicity were comparable to sirtinol, a non-specific SIRT inhibitor (SIRT1 and SIRT2), and different from EX-527, a SIRT1 specific inhibitor. This is the first report on the SIRT inhibition of ginkgolic acids and urushiols. The results reported here are in line with previously observed effects on the induction of apoptosis by this class of compounds, and the non-specific SIRT inhibition is suggested as a new mechanism for their in vitro cytotoxicity.  相似文献   
74.
Chlorotoxin is a small 36 amino-acid peptide identified from the venom of the scorpion Leiurus quinquestriatus. Initially, chlorotoxin was used as a pharmacological tool to characterize chloride channels. While studying glioma-specific chloride currents, it was soon discovered that chlorotoxin possesses targeting properties towards cancer cells including glioma, melanoma, small cell lung carcinoma, neuroblastoma and medulloblastoma. The investigation of the mechanism of action of chlorotoxin has been challenging because its cell surface receptor target remains under questioning since two other receptors have been claimed besides chloride channels. Efforts on chlorotoxin-based applications focused on producing analogues helpful for glioma diagnosis, imaging and treatment. These efforts are welcome since gliomas are very aggressive brain cancers, close to impossible to cure with the current therapeutic arsenal. Among all the chlorotoxin-based strategies, the most promising one to enhance patient mean survival time appears to be the use of chlorotoxin as a targeting agent for the delivery of anti-tumor agents. Finally, the discovery of chlorotoxin has led to the screening of other scorpion venoms to identify chlorotoxin-like peptides. So far several new candidates have been identified. Only detailed research and clinical investigations will tell us if they share the same anti-tumor potential as chlorotoxin.  相似文献   
75.
76.
Genetically modified animals continue to provide important insights into the molecular basis of health and disease. Research has focused mostly on genetically modified mice, although other species like pigs resemble the human physiology more closely. In addition, cross-species comparisons with phylogenetically distant species such as chickens provide powerful insights into fundamental biological and biomedical processes. One of the most versatile genetic methods applicable across species is CRISPR-Cas9. Here, we report the generation of transgenic chickens and pigs that constitutively express Cas9 in all organs. These animals are healthy and fertile. Functionality of Cas9 was confirmed in both species for a number of different target genes, for a variety of cell types and in vivo by targeted gene disruption in lymphocytes and the developing brain, and by precise excision of a 12.7-kb DNA fragment in the heart. The Cas9 transgenic animals will provide a powerful resource for in vivo genome editing for both agricultural and translational biomedical research, and will facilitate reverse genetics as well as cross-species comparisons.

Chickens and pigs are the most important livestock species worldwide. They are not only important sources of food, but also valuable models for evolutionary biology and biomedical science. Pigs share a high anatomical and physiological similarity with humans and are an important species for translational biomedical research, for example, in the areas of cancer, diabetes, neurodegenerative, and cardiovascular diseases (13). They also resemble the human pathophenotype more closely than rodents. For example, pig models for familial adenomatous polyposis (FAP) develop polyps in the large intestine as observed in human patients (4), whereas mouse FAP models develop them in the small intestine (5). In contrast to mammals, chickens are phylogenetically distant vertebrates from humans, but they were instrumental in the field of developmental biology due to the easy access to the embryonated egg. They are used for studying neurological and cardiovascular functions (68) and provided key findings in B cell development and graft versus host responses (911). Genetically modified livestock species also hold great promise for agriculture by offering new approaches for disease control, such as genome-edited pigs resistant to Porcine Reproductive and Respiratory Syndrome or Avian Leucosis Virus (ALV)-resistant chickens (1215).Due to the lack of fully functional embryonic stem cells, genetic engineering in pigs and chickens has been a laborious, inefficient, and time-consuming procedure (16). The generation of pigs with precise germline modifications required gene targeting in somatic cells followed by somatic cell nuclear transfer. This also is not practical in chickens, where precise alteration of the genome only became possible with recent improvements in the cultivation and manipulation of germline-competent primordial germ cells (PGCs) (1719). These modified PGCs can be injected into the blood vessel system of stage 13 to 15 (Hamburger−Hamilton [HH]) embryos to produce germline chimeras and, by further breeding, genetically modified chickens.With the advent of synthetic endonucleases such as CRISPR-Cas9 efficiency of targeted germline modification has improved in both species (2023). It still requires the generation and breeding of new founder lines, which is time consuming in large animals. To circumvent the need for generating germline-modified animals, attempts have been made to carry out genome editing directly in specific organs or tissues (2427). But this has been hampered by the need to deliver both Cas9 and the required guide RNA (gRNA) and by the limited cargo capacity of viral vectors. To bypass this drawback, Cas9 transgenic mice have been generated, requiring delivery of only the respective gRNAs (28).Here, we describe the generation of both Cas9 transgenic pigs and chickens that ubiquitously express Cas9 endonuclease and provide proof of its function in vitro and in vivo. These animals provide an innovative and efficient model for in vivo genome editing to assess gene function in health and disease.  相似文献   
77.
Heparin-induced thrombocytopenia (HIT) is a common immunological drug reaction. After exposure to heparin, some patients develop heparin dependent antibodies with no evidence of thrombosis, while others are at risk of thrombocytopenia, thrombosis, limb loss, and death. We conducted a retrospective chart review on all patients serologically positive for HIT by HPIA ELISA in a single tertiary-care hospital, to determine whether patients with malignancy had an increased risk of thrombotic complications. Medical records of 55 patients who tested positive for HIT and met clinical criteria for HIT were analyzed. All patients had been treated with unfractionated heparin. Malignancy was diagnosed in 11 patients, either at surgery or post-mortem examination. A higher rate of venous thrombosis and pulmonary embolism was observed in patients with HIT and malignant disease when compared to patients with no underlying malignancy (odds ratio 13.6, 95% CI 2.9-63.8).  相似文献   
78.
A recent systematic review of studies in the developing world has critically examined linkages from familial HIV/AIDS and associated factors such as poverty and child mental health to negative child educational outcomes. In line with several recommendations in the review, the current study modelled relationships between familial HIV/AIDS, poverty, child internalising problems, gender and four educational outcomes: non-enrolment at school, non-attendance, deficits in grade progression and concentration problems. Path analyses reveal no direct associations between familial HIV/AIDS and any of the educational outcomes. Instead, HIV/AIDS-orphanhood or caregiver HIV/AIDS-sickness impacted indirectly on educational outcomes via the poverty and internalising problems that they occasioned. This has implications for evidence-based policy inferences. For instance, by addressing such intervening variables generally, rather than by seeking to target families affected by HIV/AIDS, interventions could avoid exacerbating stigmatisation, while having a more direct and stronger impact on children's educational outcomes. This analytic approach also suggests that future research should seek to identify causal paths, and may include other intervening variables related to poverty (such as child housework and caring responsibilities) or to child mental health (such as stigma and abuse), that are linked to both familial HIV/AIDS and educational outcomes.  相似文献   
79.
International Journal of Legal Medicine - There are several metric and morphological methods available for sex estimation of skeletal remains, but their reliability and applicability depend on the...  相似文献   
80.
Clinical Rheumatology - Bone sarcoidosis is usually rare. Imaging procedures such as fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) can reveal bone...  相似文献   
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