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   18451篇
  免费   1346篇
  国内免费   22篇
耳鼻咽喉   171篇
儿科学   690篇
妇产科学   698篇
基础医学   2264篇
口腔科学   307篇
临床医学   2963篇
内科学   3276篇
皮肤病学   352篇
神经病学   1490篇
特种医学   339篇
外科学   1819篇
综合类   336篇
一般理论   19篇
预防医学   2304篇
眼科学   379篇
药学   1093篇
中国医学   22篇
肿瘤学   1297篇
  2023年   118篇
  2022年   200篇
  2021年   447篇
  2020年   330篇
  2019年   443篇
  2018年   461篇
  2017年   346篇
  2016年   394篇
  2015年   449篇
  2014年   597篇
  2013年   894篇
  2012年   1394篇
  2011年   1484篇
  2010年   773篇
  2009年   638篇
  2008年   1250篇
  2007年   1290篇
  2006年   1202篇
  2005年   1222篇
  2004年   1148篇
  2003年   1108篇
  2002年   897篇
  2001年   155篇
  2000年   156篇
  1999年   148篇
  1998年   194篇
  1997年   183篇
  1996年   138篇
  1995年   107篇
  1994年   109篇
  1993年   104篇
  1992年   117篇
  1991年   89篇
  1990年   89篇
  1989年   88篇
  1988年   66篇
  1987年   62篇
  1986年   73篇
  1985年   67篇
  1984年   98篇
  1983年   66篇
  1982年   69篇
  1981年   53篇
  1980年   61篇
  1979年   50篇
  1978年   43篇
  1977年   29篇
  1976年   31篇
  1975年   30篇
  1974年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: Contralateral prophylactic mastectomy (CPM) is the removal of a nonaffected breast in a woman with unilateral breast cancer and is effective in reducing the risk of recurrences. Little is known about women's decision-making roles regarding CPM. METHODS: Women aged 18-80 years with CPM performed at one of six health maintenance organizations between 1979 and 1999 were surveyed. We determined women's reported decision-making roles at the time of CPM, analyzed their trends over time, and explored the association between decision-making roles and psychosocial outcomes following CPM. RESULTS: We received 562 responses (response rate = 73%); 431 completed items needed for this analysis. Most respondents were white, younger than 55 years at CPM, married, and had CPM within 10 years of completing the survey. Forty-five percent made the decision to undergo CPM alone, 37% considered their doctor's opinion, 15% shared the decision with their doctor and only 3% reported their doctor primarily made the decision. Women reporting active roles were more likely to be younger (P<.0008), college educated (P<.0001) and have CPM more recently (P = .002). Compared with those sharing the decision with their doctors, women with active roles were twice as likely to be satisfied 6 months following CPM (odds ratio [OR] = 2.2, 95% confidence interval [CI] = 1.1 to 4.2) and report current concern about breast cancer (OR = 1.9, 95% CI = 1.0 to 3.4). CONCLUSIONS: Most women reported active or shared roles in decision making regarding CPM, particularly younger women, those with college education, and those with recent CPM. Women with active roles were more often satisfied in the short term but were also more likely to report current concern about breast cancer. Whether higher concern is related to insufficient input from clinicians should be explored. Prospective data are needed.  相似文献   
992.
BACKGROUND: Bilateral prophylactic mastectomy significantly decreases breast cancer risk, but complications of the procedure have only been described in single-site studies. We describe the frequency and type of complications in women who underwent bilateral prophylactic mastectomy in a multisite community-based cohort. METHODS: Women aged 18-80 years undergoing bilateral prophylactic mastectomy without a personal history of breast cancer at one of six health plans were eligible. We identified women from automated data sources, then reviewed hospital data, ambulatory notes, and other chart elements to confirm eligibility and obtain all charted information about complications and surgeries performed after prophylactic mastectomy, including reconstructive procedures. Reconstructions were characterized by type (implant vs. tissue graft). Complications were noted for a 1-year period after any surgical procedure. RESULTS: We identified 269 women with prophylactic mastectomy who were followed for a mean of 7.4 years. Their mean age was 44.9 years. Nearly 80% undertook reconstruction, most with prosthetic implants. One or more complications occurred in 64%. The most common complications were pain (35% of women), infection (17%), and seroma (17%). Women with no reconstruction had fewer complications (mean of .93) than women who had implant (2.0) or tissue graft (2.4) reconstruction procedures (differences from no reconstruction: 1.07 [95% confidence interval = 0.36 to 1.77] and 1.50 [95% confidence interval = 0.44 to 2.56] respectively). Delay of reconstruction after mastectomy was associated with a borderline-significant higher risk of complications (80.6%) compared to simultaneous reconstruction (64.0%, P = .055). CONCLUSION: We found that almost two-thirds of women undergoing bilateral prophylactic mastectomy had at least one complication following surgery. Further work should be done to minimize and to understand the effect of complications of bilateral prophylactic mastectomy.  相似文献   
993.
A review of the diagnosis and management of male breast cancer   总被引:8,自引:0,他引:8  
Giordano SH 《The oncologist》2005,10(7):471-479
Male breast cancer is an uncommon disease although the incidence has increased over the past 25 years. As with many other rare "orphan" diseases, male breast cancer is understudied. The rarity of the disease precludes prospective randomized clinical trials. In addition, few researchers and minimal funding have focused on breast cancer in men, but further work is clearly needed to better understand this disease. It shares many similarities with breast cancer in women; yet some clear differences have emerged. In this article, the latest information on the epidemiology, biology, and treatment of male breast cancer is reviewed.  相似文献   
994.
We showed in this study that cells deficient of the BRCA1-associated BACH1 helicase, also known as BRIP1, failed to elicit homologous recombination (HR) after DNA double-stranded breaks (DSBs). BACH1-deficient cells were also sensitive to mitomycin C (MMC) and underwent MMC-induced chromosome instability. Moreover, we identified a homozygous nonsense mutation in BACH1 in a FA-J patient-derived cell line and could not detect BACH1 protein in this cell line. Expression of wild-type BACH1 in this cell line reduced the accumulation of cells at G2/M phases following exposure to DNA crosslinkers, a characteristic of Fanconi anemia (FA) cells. These results support the conclusion that BACH1 is FANCJ.  相似文献   
995.
996.
OBJECTIVES: Chronic obstructive pulmonary disease (COPD) as a cause of disability with subsequent costs remains poorly recognized. The small, growing body of literature on COPD shows that it is one of the leading causes of missed work.greater than asthma or diabetes. However, much less is known about the impact of COPD on long-term disability (LTD). Because the health care burden for disabled, working-age patients will fall heavily on managed care organizations, better estimates of the economic and pharmacoeconomic costs of COPD are required. We seek to improve understanding of the burden of COPD on several national LTD programs. METHODS: We reviewed occupational health and disability literature and government statistics to determine how long-term, respiratory-related disability is addressed by disability pension programs in 8 developed countries (Canada, France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States). We then applied respiratory-specific disability definitions to country-specific population and pension information to estimate the potential burden of COPD on LTD insurance programs in each country. RESULTS: Comprehensive, relevant data to evaluate respiratory-related disability are lacking. Of the study countries, only the United States has explicit respiratory specific criteria for disability eligibility, which are based solely on spirometry. We estimate that the total burden of COPD in the study countries may range from 5 billion dollars to as high as 25 billion dollars per year if all persons who met U.S. eligibility criteria for respiratory-related disability were granted compensation. CONCLUSION: The potential burden of COPD on LTD programs may be large. The lack of standard criteria for respiratory-related disability may lead to underrecognition of COPD's true potential impact. Further work is needed to develop consistent and cost-effective ways to measure the impact of COPD and to assist in disability determination for COPD patients.  相似文献   
997.
KTX 0101 is the sodium salt of the physiological ketone, D-beta-hydroxybutyrate (betaOHB). This neuroprotectant, which has recently successfully completed clinical Phase IA evaluation, is being developed as an intravenous infusion fluid to prevent the cognitive deficits caused by ischemic foci in the brain during cardiopulmonary bypass (CPB) surgery. KTX 0101 maintains cellular viability under conditions of physiological stress by acting as a "superfuel" for efficient ATP production in the brain and peripheral tissues. Unlike glucose, this ketone does not require phosphorylation before entering the TCA cycle, thereby sparing vital ATP stores. Although no reliable models of CPB-induced ischemia exist, KTX 0101 is powerfully cytoprotectant under the more severe ischemic conditions of global and focal cerebral ischemia, cardiac ischemia and lung hemorrhage. Neuroprotection has been demonstrated by reductions in infarct volume, edema, markers of apoptosis and functional impairment. One significant difference between KTX 0101 and other potential neuroprotectants in development is that betaOHB is a component of human metabolic physiology which exploits the body's own neuroprotective mechanisms. KTX 0101 also protects hippocampal organotypic cultures against early and delayed cell death in an in vitro model of status epilepticus, indicating that acute KTX 0101 intervention in this condition could help prevent the development of epileptiform foci, a key mechanism in the etiology of intractable epilepsy. In models of chronic neurodegenerative disorders, KTX 0101 protects neurons against damage caused by dopaminergic neurotoxins and by the fragment of beta-amyloid, Abeta(1-42), implying possible therapeutic applications for ketogenic strategies in treating Parkinson's and Alzheimer's diseases. Major obstacles to the use of KTX 0101 for long term therapy in chronic disorders, e.g., Parkinson's and Alzheimer's diseases, are the sodium loading problem and the need to administer it in relatively large amounts because of its rapid mitochondrial metabolism. These issues are being addressed by designing and synthesizing orally bioavailable multimers of betaOHB with improved pharmacokinetics.  相似文献   
998.
The aim of this study was to identify genomic aberrations in endometrial cancer cells treated with the phyto-estrogenic compounds tectorigenin, irigenin and apigenin and to compare with those treated with beta-estradiol using array-based comparative genomic hybridisation (array CGH). The microarray contains 287 targets and includes telomeres, microdeletions, oncogenes and tumour suppressor genes and has increased mapping resolution compared to conventional CGH. An endometrial cancer cell line (Ishikawa) was cultured and treated with the phyto-estrogens. Treated cells were examined using the CGH microarray. Over 20 % of the array genes were aberrated in the cells treated with beta-estradiol, tectorigenin and irigenin compared to 3 % in those treated with the same concentration of apigenin. Protein kinase c zeta form, insulin, insulin receptor and protein-tyrosine phosphatase non-receptor-type 1 which are involved in insulin metabolism were aberrated by tectorigenin and irigenin. Apigenin may play a role in the treatment of endometrial cancer and in the treatment of postmenopausal women. Further studies in normal endometrium and primary endometrial cancer cells are needed to elucidate the role of the phyto-estrogens.  相似文献   
999.
Prostate specific membrane antigen (PSMA) is a well-characterized glycoprotein overexpressed on the surface of prostate cancer cells. The novel radiopharmaceutical 1,4,7,10-tetraazacyclododecane-N,N',N',N'-tetraacetic acid (DOTA) radiolabeled with Yttrium (90Y) or Indium (111In) conjugated with anti-PSMA genetically engineered humanized monoclonal antibody (huJ591) has been investigated to target prostate cancer cells. The immunoconjugate of huJ591 with the analog of the cytotoxic drug maytansine, DM1 (N2'-deacetyl-N2'-(3-mercapto-1-oxopropyl)-maytansine) has also been developed at Millennium Pharmaceuticals. Activation of the DOTA molecule, resulting in 1,4,7,10-tetraazacyclododecane-N,N',N',N'-tetraacetic acid mono-(N-hydroxysuccinimidyl) ester (DOTA-NHS), allows conjugation with the anti-PSMA antibody through lysine residues in the antibody. The objectives of the study were to characterize the unstable chemical properties of DOTA-NHS before bioconjugation with huJ591, evaluate the binding profiles of DOTA to huJ591, and calculate trace metal elements (which may disturb 90Y or 111In labeling efficacy to the DOTA-huJ591 conjugate). A novel LC/MS/MS (Liquid Chromatography/Mass Spectrometry/Mass Spectrometry) quantitation method was developed to monitor the stability of DOTA-NHS in solid form and its bioconjugation chemistry reactions. Meanwhile, metal analysis was quantified by Inductively Coupled Plasma Mass Spectrometry (ICP/MS) to estimate the amounts of trace metals in DOTA-NHS and ensure radiolabeling efficiency of the conjugate at the radiopharmacy. MALDI-TOF MS (Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry) was used to identify levels of DOTA or DM1conjugation in DOTA-huJ591 and DM1-huJ591 conjugates, respectively.  相似文献   
1000.
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