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   6161篇
  免费   395篇
  国内免费   14篇
耳鼻咽喉   74篇
儿科学   147篇
妇产科学   118篇
基础医学   853篇
口腔科学   54篇
临床医学   561篇
内科学   1350篇
皮肤病学   48篇
神经病学   561篇
特种医学   184篇
外国民族医学   3篇
外科学   902篇
综合类   35篇
一般理论   3篇
预防医学   622篇
眼科学   58篇
药学   579篇
中国医学   2篇
肿瘤学   416篇
  2023年   28篇
  2022年   53篇
  2021年   112篇
  2020年   64篇
  2019年   125篇
  2018年   154篇
  2017年   140篇
  2016年   150篇
  2015年   146篇
  2014年   200篇
  2013年   257篇
  2012年   399篇
  2011年   368篇
  2010年   201篇
  2009年   201篇
  2008年   359篇
  2007年   344篇
  2006年   296篇
  2005年   298篇
  2004年   265篇
  2003年   239篇
  2002年   221篇
  2001年   151篇
  2000年   157篇
  1999年   107篇
  1998年   55篇
  1997年   49篇
  1996年   44篇
  1995年   40篇
  1994年   46篇
  1993年   37篇
  1992年   108篇
  1991年   86篇
  1990年   94篇
  1989年   102篇
  1988年   79篇
  1987年   69篇
  1986年   59篇
  1985年   62篇
  1984年   51篇
  1983年   35篇
  1982年   36篇
  1981年   28篇
  1979年   26篇
  1978年   33篇
  1976年   29篇
  1975年   29篇
  1974年   29篇
  1973年   28篇
  1970年   22篇
排序方式: 共有6570条查询结果,搜索用时 15 毫秒
81.
Summary During the use of a vertical flow enclosure of our own design for almost five years, bacteriological studies and the infection rates in different groups of patients have taught us the following:1. In a clean room operating theatre, the use of a respired air exhaust system improves the sterility compared with the use of ordinary masks. In a vertical flow enclosure, the chest, the arms, and the hands of the team are contaminated from respired airborne bacteria if helmets, etc., are not worn.2. In our vertical flow enclosure with almost continuous absolute sterility of the air, the infection rate in primary total hip replacement is very low and less than 1%, including early and late infections. Antibiotics have not been used.In secondary surgery, i.e., total hip replacement in hip joints previously operated upon, the infection rate is markedly higher, probably because of a flare-up of latent infection.Clean room surgery therefore, can only prevent air borne contamination, and no more; but this is very valuable.3. Vertical flow enclosures of the Charnley-Howorth (1975) and Weber et al. (1971) type provide considerable improvement in sterility of the air compared with adaptations of more conventional theatres. We recommend that these facilities be made available for implant surgery. It is also necessary to have a stringent operational policy with cooperation and discipline on the part of all members of the theatre team.
Résumé Durant l'utilisation, depuis plus de 5 ans, de la serre stérile à flux laminaire vertical que nous avons construite, nous avons pratiqué des études bactériologiques et pu comparer les taux d'infection suivant les groupes de patients.1. Dans une salle d'opération propre, la stérilité est considérablement améliorée par le port de casques possédant un système d'aspiration de l'air expiré, ceci par rapport au port de masques ordinaires. De plus, si l'on ne porte pas le casque dans une serre à flux laminaire vertical, le tronc, les mains et les membres supérieurs de l'équipe chirurgicale sont contaminés par les microbes en suspension dans l'air expiré.2. Dans notre serre où l'air est pratiquement stérile, le taux d'infections précoces et tardives est inférieur à 1% dans les arthroplasties de la hanche, et cela sans utilisation d'antibiotiques.Lors d'interventions dites secondaires, c'est-à-dire dans les cas déjà opérés au préalable, par exemple par ostéotomie, ostéosynthèse, etc., le taux d'infection est plus élevé. On doit probablement en rechercher la cause dans une contamination de la plaie lors de la première intervention, l'infection alors à l'état latent pouvant se réveiller à la faveur d'une nouvelle opération.En opérant dans une serre stérile, on peut donc prévenir la contamination par l'air ambiant, mais pas plus. Cela est cependant déjà très appréciable.3. Comparées aux salles d'opération conventionnelles modernes, les serres stériles à flux laminaire vertical, comme celle de Charnley-Howorth (1975) et Weber-Meierhans (1971), améliorent considérablement la stérilité de l'air. Surtout pour la chirurgie prothétique de la hanche, dont les risques d'infection sont élevés, nous recommandons l'emploi de ce genre d'installation. Mais il est nécessaire que tous les membres de l'équipe chirurgicale adoptent des règles très strictes de discipline.
  相似文献   
82.
The chloride:phosphate ratio is of only limited value in aiding the clinician in the differential diagnosis of hypercalcemia. The use of thiazide diuretics may cause hypercalcemia with a chloride:phosphate ratio said to be consistent with a diagnosis of primary hyperparathyroidism. Parathormone assay remains the "gold standard" for definitive diagnosis of hyperparathyroidism.  相似文献   
83.
84.
A frequent complaint among health care professionals about ADE reporting programs is that they never know what happens to the information they took the time and effort to report. In the Mississippi ADE program, physicians appreciated the feedback they were provided--in letter form--indicating the ultimate disposition of the reported information. Also, a regular newsletter summarizing the number and types of reports and the drugs involved was well received. This vehicle was also used to educate physicians about new drugs on the market that warranted closer scrutiny. Reminder posters placed at strategic points around the hospital and periodic inservices on the program are effective in maintaining a level of awareness about the importance of ADE monitoring and its impact on the quality of care.  相似文献   
85.
The "Duplizit?tstheorie" of Meyer zum Gottesberge (1948) states that signal processing takes place at low sound intensities on the nerve fibers of the outer hair cells, whereas at high sound intensities on the nerve fibers of the inner hair cells. The discovery of oto-acoustic emissions by Kemp (1978) makes a modification of the "Duplizit?tstheorie" necessary. The outer hair cells are supposed to be motor-drives final control elements to enhance the sensitivity of inner hair cells. Thus outer hair cells do not serve for the direct transmission of information in the sense of neural coding. Signal processing takes place at all intensities exclusively on the nerve fibers of the inner hair cells.  相似文献   
86.
The long-term consequences of accidental chlorine gas exposure have been investigated, mainly in the community setting, among persons exposed as a result of a nearby chlorine spill. This circumstance is not analogous to the more frequent chlorine or chlorine dioxide gas overexposures that occur commonly in pulpmills over a background of a low level of gas exposure. To investigate the respiratory health consequences of these accidental exposures ("chlorine gassing") in the industrial setting, we carried out a cross-sectional respiratory health survey among workers at a British Columbia coastal pulpmill and a nearby rail maintenance yard. A greater proportion of pulpmill workers were unavailable for study because of illness (10.5% versus 2.4% in the railyard, p less than 0.01). Procedures involved simple spirometry, respiratory symptom assessment, and measurement of average levels of air contaminants. Average chlorine levels in the pulpmill were below 1 ppm; however, 60% of the pulpmill workers reported one or more accidental "chlorine gassing" incidents. Pulpmill workers who reported being "gassed" were significantly more likely to report wheezing on occasion than were other pulpmill workers and railyard workers (rate for these three groups: nonsmokers: 8, 2, 1%; ex-smokers: 17, 11, 7%; current smokers: 42, 21, 19%; p less than 0.05). No significant lung function differences were found between the overall pulpmill group and the railyard workers; however, nonsmoking and formerly smoking pulpmill workers who reported being "gassed" had significantly lower average midmaximal flow rate and FEV1/FVC ratio than did their counterparts in the remainder of the pulpmill population (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
87.
88.
89.
This account of the highlights of the eighth St Gallen (Switzerland) meeting in 2003 emphasizes new information that has emerged during the 2 years since the seventh meeting in 2001. This article should be read in conjunction with the report of that earlier meeting. Recommendations for patient care are so critically dependent on assessment of endocrine responsiveness that the importance of high-quality steroid hormone receptor determination and standardized quantitative reporting cannot be overemphasized. The International Consensus Panel modified the risk categories so that only endocrine receptor-absent status was sufficient to reclassify an otherwise low-risk, node-negative disease into the category of average risk. Absence of steroid hormone receptors also was recognized as indicating endocrine nonresponsiveness. Some important areas highlighted at the recent meeting include: (1) recognition of the separate nature of endocrine-nonresponsive breast cancer-both invasive cancers and ductal carcinoma-in-situ; (2) improved understanding of the mechanisms of acquired endocrine resistance, which offer exciting prospects for extending the impact of successful sequential endocrine therapies; (3) presentation of high-quality evidence indicating that chemotherapy and tamoxifen should be used sequentially rather than concurrently; (4) availability of a potential alternative to tamoxifen for treatment of postmenopausal women with endocrine-responsive disease; and (5) the promise of newly defined prognostic and predictive markers.  相似文献   
90.
Early events leading to renal injury in obese Zucker (fatty) rats with type II diabetes. BACKGROUND: More than half of the new patients admitted to dialysis therapy in some centers are diagnosed with type IIb diabetes, that is, diabetes associated with obesity. This study searched for a common final pathway of renal damage in this progressive renal disease. METHODS: The evolution of biochemical and morphological renal changes was examined in 6- to 60-week-old Zucker rats (fa/fa-rats), a model of obesity associated with type II diabetes. RESULTS: fa/fa-rats exhibited pronounced hyperinsulinemia and hyperlipidemia at 6 weeks and became diabetic after 14 weeks of age. Significant focal segmental glomerulosclerosis was first noted in 18-week-old fa/fa-rats and tubulointerstitial damage and proteinuria in 40-week-old fa/fa-rats. A comparison of kidneys of six-week-old fa/fa-and lean control (Fa/?) rats by immunohistology revealed a 1.8-fold increase in glomerular monocyte/macrophage counts in fa/fa-rats and a significant increase in de novo desmin expression in podocytes. Electron microscopy demonstrated an increase in the number of podocyte mitochondria and intracytoplasmic protein and fat droplets. Podocyte desmin scores markedly increased until week 18 in fa/fa-rats, whereas glomerular monocyte/macrophage counts peaked at 3.2-fold at week 14. Podocyte desmin expression, but not glomerular macrophage infiltration, correlated with damage in adjacent tubular cells, as evidenced by their de novo expression of vimentin. Progressive glomerular hypertrophy was detected in fa/fa-rats after 10 weeks. GBM width was significantly increased in 14-week-old fa/fa-rats as compared with lean controls. Mesangial cell activation (de novo expression of alpha-smooth muscle actin) and proliferation was low to absent throughout the observation period in fa/fa-rats. Renal cell death counts (TUNEL) remained unchanged in 6- to 40-week-old fa/fa-rats. Tubulointerstitial myofibroblast formation and matrix accumulation occurred late during the study duration in fa/fa-rats. CONCLUSION: These data suggest that early progressive podocyte damage and macrophage infiltration is associated with hyperlipidemia and type IIb diabetes mellitus, and antedates both the development of glomerulosclerosis and tubulointerstitial damage.  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