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   1756篇
  免费   111篇
  国内免费   9篇
耳鼻咽喉   23篇
儿科学   67篇
妇产科学   17篇
基础医学   175篇
口腔科学   30篇
临床医学   227篇
内科学   326篇
皮肤病学   33篇
神经病学   108篇
特种医学   72篇
外科学   314篇
综合类   15篇
预防医学   177篇
眼科学   30篇
药学   117篇
中国医学   6篇
肿瘤学   139篇
  2023年   24篇
  2022年   48篇
  2021年   106篇
  2020年   58篇
  2019年   52篇
  2018年   55篇
  2017年   46篇
  2016年   44篇
  2015年   43篇
  2014年   61篇
  2013年   68篇
  2012年   89篇
  2011年   89篇
  2010年   59篇
  2009年   28篇
  2008年   49篇
  2007年   58篇
  2006年   51篇
  2005年   55篇
  2004年   54篇
  2003年   41篇
  2002年   47篇
  2001年   30篇
  2000年   35篇
  1999年   33篇
  1996年   8篇
  1995年   9篇
  1993年   8篇
  1992年   29篇
  1991年   32篇
  1990年   34篇
  1989年   25篇
  1988年   37篇
  1987年   36篇
  1986年   30篇
  1985年   29篇
  1984年   17篇
  1983年   18篇
  1980年   10篇
  1979年   19篇
  1978年   10篇
  1977年   15篇
  1976年   10篇
  1975年   13篇
  1974年   15篇
  1973年   8篇
  1972年   16篇
  1970年   8篇
  1969年   9篇
  1968年   12篇
排序方式: 共有1876条查询结果,搜索用时 46 毫秒
31.
Archives of Women's Mental Health - A Correction to this paper has been published: https://doi.org/10.1007/s00737-021-01122-7  相似文献   
32.
Ribavirin and remdesivir have been preclinically reported as potential drugs for the treatment of SARS-CoV-2 infection, while light silver tetrylene complexes (NHEPh–AgCl and (NHEPh–AgCl)2 with E = C, Si, and Ge) have gained significant interest due to their promising applicability on the cytological scale. Firstly, the structures and bonding states of silver–tetrylene complexes (NHE–Ag) and bis-silver–tetrylene complexes (NHE–Ag-bis) were investigated using density functional theory (DFT) at the BP86 level with the def2-SVP and def2-TZVPP basis sets. Secondly, the inhibitory capabilities of the carbene complexes (NHC–Ag and NHC–Ag-bis) and the two potential drugs (ribavirin and remdesivir) on human-protein ACE2 and SARS-CoV-2 protease PDB6LU7 were evaluated using molecular docking simulation. The carbene ligand NHC bonds in a head-on configuration with AgCl and (AgCl)2, whereas, the other NHE (E = Si and Ge) tetrylene ligands bond in a side-on mode to the metal fragments. The bond dissociation energy (BDE) of the NHE–Ag bond in the complex families follows the order of NHC–Ag > NHSi–Ag > NHGe–Ag and NHSi–Ag-bis > NHGe–Ag-bis > NHC–Ag-bis. The natural bond orbital analysis implies that the [NHEPh→AgCl] and [(NHEPh)2→(AgCl)2] donations are derived mainly from the σ- and π-contributions of the ligands. The docking results indicate that both the ACE2 and PDB6LU7 proteins are strongly inhibited by silver–carbene NHC–Ag, bis-silver–carbene NHC–Ag-bis, ribavirin, and remdesivir with the docking score energy values varying from −17.5 to −16.5 kcal mol−1 and −16.9 to −16.6 kcal mol−1, respectively. The root-mean-square deviation values were recorded to be less than 2 Å in all the calculated systems. Thus, the present study suggests that silver–carbene NHC–Ag and bis-silver–carbene NHC–Ag-bis complexes are potential candidates to inhibit ACE2 and PDB6LU7, and thus potentially conducive to prevent infection caused by the SARS-CoV-2 virus.

Simultaneous inhibition of silver–carbene complexes to ACE2 and PDB6LU7 is conducive for the prevention of SARS-CoV-2 infection: a virtual prediction.  相似文献   
33.

Background

Intervertebral disc degeneration is a common condition with few inexpensive and effective modes of treatment, but current investigations seek to clarify the underlying process and offer new treatment options. It will be important for physicians to understand the molecular basis for the pathology and how it translates to developing clinical treatments for disc degeneration. In this review, we sought to summarize for clinicians what is known about the molecular processes that causes disc degeneration.

Results

A healthy disc requires maintenance of a homeostatic environment, and when disrupted, a catabolic cascade of events occurs on a molecular level resulting in upregulation of proinflammatory cytokines, increased degradative enzymes, and a loss of matrix proteins. This promotes degenerative changes and occasional neurovascular ingrowth potentially contributing to the development of pain. Research demonstrates the molecular changes underlying the harmful effects of aging, smoking, and obesity seen clinically while demonstrating the variable influence of exercise. Finally, oral medications, supplements, biologic treatments, gene therapy, and stem cells hold great promise but require cautious application until their safety profiles are better outlined.

Conclusions

Intervertebral disc degeneration occurs where there is a loss of homeostatic balance with a predominantly catabolic metabolic profile. A basic understanding of the molecular changes occurring in the degenerating disc is important for practicing clinicians because it may help them to inform patients to alter lifestyle choices, identify beneficial or harmful supplements, or offer new biologic, genetic, or stem cell therapies.  相似文献   
34.
35.
36.
A controlled antegrade dissection and reentry technique is the most commonly employed crossing strategy for long coronary chronic total occlusions. The development of compressive hematoma is a recognized complication and results in the impairment of distal vessel visualization and hinders successful reentry attempts. We describe a novel technique utilizing a widely available microcatheter to decompress the subintimal hematoma to restore distal visualization and allow successful reentry.  相似文献   
37.
The objective of this study is to compare neuropsychological test performance before and after HIV-1 seroconversion in order to identify possible acute changes in psychomotor speed, memory, attention, and concentration secondary to seroconversion. The study utilized mixed effects models to examine longitudinal neuropsychological test data. We conducted a nested cohort study of 362 male HIV-1 seroconverters enrolled in the Multicenter AIDS Cohort Study. We used linear mixed models with random subject effects to compare repeated neuropsychological test outcomes from 5 years before seroconversion to 2 years after seroconversion on the Trail Making Test (parts A and B), Symbol-Digit Test, Grooved Pegboard (dominant and non-dominant hands), Stroop Color-Interference Test, Rey Auditory Verbal Learning Test, and the CalCAP Reaction Time Test. We found no significant changes in the time-dependent score after seroconversion for the majority of neuropsychological tests used in the Multicenter AIDS Cohort Study. There was a significant change in time trend after seroconversion on part B of the Trail Making Test (p?=?0.042), but the difference only represented a 2 % decrease in performance. We found the following characteristics to be associated with worse neuropsychological test performance: lower education levels, history of depression, older age, and no previous neurocognitive testing (p?<?.05). Our results suggest that despite a 50 % decrease in CD4 cell count immediately following infection, HIV-1 does not appear to have a measurable effect on psychomotor or complex cognitive processing for up to 2 years following infection, using this set of neurocognitive measures.  相似文献   
38.
39.
Fabrication of a high-performance room-temperature (RT) gas sensor is important for the future integration of sensors into smart, portable and Internet-of-Things (IoT)-based devices. Herein, we developed a NO2 gas sensor based on ultrathin MoS2 nanoflowers with high sensitivity at RT. The MoS2 flower-like nanostructures were synthesised via a simple hydrothermal method with different growth times of 24, 36, 48, and 60 h. The synthesised MoS2 nanoflowers were subsequently characterised by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The petal-like nanosheets in pure MoS2 agglomerated to form a flower-like structure with Raman vibrational modes at 378 and 403 cm−1 and crystallisation in the hexagonal phase. The specific surface areas of the MoS2 grown at different times were measured by using the Brunauer–Emmett–Teller method. The largest specific surface area of 56.57 m2 g−1 was obtained for the MoS2 nanoflowers grown for 48 h. This sample also possessed the smallest activation energy of 0.08 eV. The gas-sensing characteristics of sensors based on the synthesised MoS2 nanostructures were investigated using oxidising and reducing gases, such as NO2, SO2, H2, CH4, CO and NH3, at different concentrations and at working temperatures ranging from RT to 150 °C. The sensor based on the MoS2 nanoflowers grown for 48 h showed a high gas response of 67.4% and high selectivity to 10 ppm NO2 at RT. This finding can be ascribed to the synergistic effects of largest specific surface area, smallest crystallite size and lowest activation energy of the MoS2-48 h sample among the samples. The sensors also exhibited a relative humidity-independent sensing characteristic at RT and a low detection limit of 84 ppb, thereby allowing their practical application to portable IoT-based devices.

Controlled synthesis of ultrathin MoS2 nanoflowers is crucial to develop a high-performance room-temperature NO2 gas sensor for the future integration of sensors into smart, portable and Internet-of-Things (IoT)-based devices.  相似文献   
40.
In this study, the effect of graphene nanoplatelet (GNP) size on the microstructure and hardness of the electrodeposited nickel–graphene nanocomposite coatings were investigated. GNPs with different sizes were prepared by using a high energy ball milling technique. The experimental result revealed the high energy ball milling technique could reduce the size, increase the surface area, and improve the dispersion ability of GNPs. The microstructure, hardness, and components of the nanocomposite coatings were greatly affected by GNP sizes. The highest microhardness was measured to be 273 HV for the nanocomposite coatings containing 5 h-milled GNPs, which is increased up to ∼47% compared to pristine Ni coating. The enhancement in the hardness is attributed to the uniform dispersion of the small GNP sizes inside the Ni matrix and the Ni grain size reduction when using milled GNPs.

The effect of graphene nanoplatelet size on the microstructure and hardness of electrodeposited nickel–graphene nanocomposite coatings was investigated.  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