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   3634篇
  免费   570篇
  国内免费   41篇
耳鼻咽喉   1篇
儿科学   124篇
妇产科学   285篇
基础医学   566篇
口腔科学   8篇
临床医学   440篇
内科学   504篇
皮肤病学   26篇
神经病学   15篇
特种医学   18篇
外科学   1384篇
综合类   312篇
一般理论   5篇
预防医学   362篇
眼科学   17篇
药学   140篇
中国医学   22篇
肿瘤学   16篇
  2024年   3篇
  2023年   73篇
  2022年   84篇
  2021年   224篇
  2020年   235篇
  2019年   235篇
  2018年   185篇
  2017年   243篇
  2016年   189篇
  2015年   185篇
  2014年   259篇
  2013年   273篇
  2012年   190篇
  2011年   202篇
  2010年   146篇
  2009年   135篇
  2008年   130篇
  2007年   159篇
  2006年   135篇
  2005年   107篇
  2004年   102篇
  2003年   106篇
  2002年   72篇
  2001年   71篇
  2000年   59篇
  1999年   62篇
  1998年   40篇
  1997年   44篇
  1996年   38篇
  1995年   47篇
  1994年   29篇
  1993年   28篇
  1992年   30篇
  1991年   13篇
  1990年   21篇
  1989年   21篇
  1988年   13篇
  1987年   8篇
  1986年   8篇
  1985年   7篇
  1984年   5篇
  1983年   12篇
  1982年   6篇
  1981年   3篇
  1980年   5篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有4245条查询结果,搜索用时 125 毫秒
31.
BACKGROUND: The aim of the study was to assess infertile couples' attitudes toward the procedures of embryo donation (ED) and to identify factors predicting interest in donation. METHODS: Fifty-one couples who had received IVF treatment and had subsequently had embryos cryopreserved for >3 years were located and sent written information about the procedures for ED and possible implications of donation. A total of 49 couples agreed to participate in the study with 36 women and 31 men subsequently returning questionnaires describing their reasons for not claiming unused embryos and attitudes towards ED. RESULTS: Patients were supportive of donor screening procedures, but less comfortable sharing non-identifying information. Comfort levels declined as information became increasingly personal. Support for unconditional (i.e. the donation of embryos without conditions attached) and conditional (i.e. where couples could limit the donation of their embryos to persons/couples according to their preferences) models of donation was highly polarized and a substantial minority expressed strong opposition to each model. Willingness to donate was associated with greater comfort about disclosing personal information, a desire to know the outcome of donation and willingness to have future contact with a child, but not with current family size. CONCLUSIONS: Comfort in sharing information with a recipient couple is more important than acceptance of screening procedures, or attainment of family size goals in predicting willingness to donate embryos. Offering the option of conditional donation could increase the acceptability of ED for some patients.  相似文献   
32.
Egg-sharing in assisted conception: ethical and practical considerations   总被引:1,自引:5,他引:1  
The present acute shortage of eggs for donation cannot be overcomeunless adequate guidelines are set to alleviate the anxietiesregarding payments, in cash or kind, to donors. The currentHuman Fertilisation and Embryology Authority (HFEA) guidelinesdo not allow direct payment to donors but accept the provisionof lower cost or free in-vitro fertilization (IVF) treatmentto women in recognition of oocyte donation to anonymous recipients.Egg-sharing achieved in this way enables two infertile couplesto benefit from a single surgical procedure. However, the practicalguidelines related to this approach are ill-defined at the presenttime leading to some justifiable uncertainty. A pilot studywas therefore undertaken in order to establish the place ofegg-sharing in an assisted conception programme. The currentHFEA guidelines on medical screening of patients, counselling,age and rigid anonymity between the donor and recipient werefollowed. The study involved 55 women (25 donors and 30 recipients)in 73 treatment cycles involving fresh and frozen-thawed embryos.Donors were previous IVF patients who, regardless of their abilityto pay, shared their eggs equally with matched anonymous recipients.They paid only for their consultations and tests right up tothe point of being matched with a recipient The sole recipientpaid the cost applicable in egg donation of a single egg collection,although both received embryo transfers. The results indicatethat although the recipients were older than the donors (41.4± 0.9 versus 31.6 ± 0.5 years), and there wasno difference in the mean number of eggs allocated, the percentagefertilization rates, or the mean number of embryos transferred,there were more births per patient amongst recipients than amongstdonors (30 versus 20%). We conclude that providing the donorsare selected carefully, this scheme whereby a sub-fertile donorhelps a sub-fertile recipient is a very constructive way ofsolving the problem of the shortage of eggs for donation. Thereare also the advantages of including a group of women who wouldotherwise be denied treatment Problems related to ‘patientcoercion’ can, in our view, be fully overcome by the applicationof strict common-sense safeguards. The ideal of pure altruismis not without its medical and moral risk. The success of egg-sharingdepends on shared interests and a degree of altruism betweenthe donor, the recipient and the centre. The current HFEA guidelinesshould be applauded for enabling a highly effective conceptof mutual help to develop.  相似文献   
33.
BACKGROUND: No adequate enteral sensitization models are available to study food allergy and the allergenicity of food proteins. To further validate an enteral brown Norway (BN) rat sensitization model under development, we studied specific protein recognition to determine whether a comparable pattern of proteins is recognized by the rat immune system and the human immune system. METHODS: The animals were exposed to either ovalbumin as a positive reference control, hen's egg-white-protein extract, or a cow's milk preparation by daily gavage dosing (0.5, 1, 2.5, 5, 10, or 15 mg protein per rat/day) for 9 weeks. No adjuvants were used during the sensitization studies. The specificities of antibodies against hen's egg-white proteins or cow's-milk proteins in sera from orally sensitized rats and food-allergic patients were studied and compared by immunoblotting. RESULTS: The IgG and IgE antibodies to hen's egg-white proteins and cow's-milk proteins present in sera from orally sensitized rats and food-allergic patients showed a comparable pattern of protein recognition. CONCLUSIONS: Upon daily intragastric exposure to food allergens, the specificities of the induced antibody responses in the BN rat resemble those found in food-allergic patients. These studies add further support to the hypothesis that the BN rat may provide a suitable animal model for food allergy research and research on the allergenicity of food proteins.  相似文献   
34.
35.
Expression of CD4-like molecule on vitelline membrane of murine eggs was demonstrated by indirect immunofluorescence (IIF) test and immunoprecipitation corresponding to the expression of major histocompatibility complex (MHC) class II molecule on murine sperm detected by immunoblotting. This molecule showed slightly larger size than that of the authentic CD4 molecule from T-cells on SDS-PAGE. This molecule was suggested to bind to MHC class II structure on sperm during fertilization because anti-CD4 monoclonal antibody (mAb) blocked in vitro fertilization (IVF). In addition, src-related tyrosine protein kinase (p56lck) was demonstrated in the inner vitelline membrane of eggs by means of IIF with anti-p56lck mAb and immune-complex kinase assay. This molecule was suggested to be associated with CD4-like molecule.  相似文献   
36.
《Value in health》2021,24(9):1360-1376
ObjectivesTo identify published economic evaluations of interventions aimed at preventing, diagnosing, or treating food allergies in children.MethodsWe examined economic evaluations published from 2000 to 2019. Data analyzed included: food allergy type, study population/setting, intervention/comparator, and economic evaluation details. Quality assessment used reporting and economic modeling checklists. Two reviewers simultaneously undertook article screening, data extraction, and quality assessment.Results17 studies were included: 8 peanut allergy (PA) studies, 8 cow’s milk allergy (CMA) studies, and 1 egg allergy (EA) study. All PA studies reported incremental costs per quality-adjusted life-year gained for diagnostic strategies, management pathways for peanut exposure, and immunotherapies. Immunotherapies rendered inconsistent cost-effectiveness results. CMA studies reported costs per symptom-free day or probability of developing CMA tolerance. Cost-effectiveness of extensively hydrolyzed casein formula for CMA treatment was consistently demonstrated. Early introduction of cooked egg in first year of life dominated all EA prevention strategies. Quality assessment showed average noncompliance for 3.5 items/study (range 0-11) for modeling methods and 3.4 items/study (range 0-8) for reporting quality. Key quality concerns included limited justification for model choice, evidence base for model parameters, source of utility values, and representation of uncertainty.ConclusionRecent cost-effectiveness literature of interventions in PA, CMA, and EA is limited and diverse. Interventions for diagnosis and treatment of CMA and prevention of EA were generally cost-effective; however, results for PA were variable and dependent on effectiveness and utility values used. There is a need to expand economic evaluation of interventions for childhood food allergy and to improve methods and reporting.  相似文献   
37.
目的:了解有偿和无偿献者HBsAg、抗-HCV、抗-HIV I/II测定结果。方法:均采用酶联吸附试验(ELISA)法。结果:有偿和无偿献血者之HBsAg阳性率分别为2.39%和3.32%,抗-HCV阳性率分别为4.81%和2.89%,抗-HIV I/II结果均为阴性。结论:有偿与无偿献血者之间的HBsAg和抗-HCV阳性率比较均有显著性差异(t值分别为2.8633和2.3638,P<0.05)。  相似文献   
38.
39.
Between 2013 and 2019, there was an increase in the consent rate for organ donation in the UK from 61% to 67%, but this remains lower than many European countries. Data on all family approaches (16,896) for donation in UK intensive care units or emergency departments between April 2014 and March 2019 were extracted from the referral records and the national potential donor audit held by NHS Blood and Transplant. Complete data were available for 15,465 approaches. Consent for donation after brain death was significantly higher than for donation after circulatory death, 70% (4260/6060) vs. 60% (5645/9405), (OR 1.58, 95%CI 1.47–1.69). Patient ethnicity, religious beliefs, sex and socio-economic status, and knowledge of a patient's donation decision were strongly associated with consent (p < 0.001). These factors should be addressed by medium- to long-term strategies to increase community interventions, encouraging family discussions regarding donation decisions and increasing registration on the organ donor register. The most readily modifiable factor was the involvement of an organ donation specialist nurse at all stages leading up to the approach and the approach itself. If no organ donation specialist nurse was present, the consent rates were significantly lower for donation after brain death (OR 0.31, 95%CI 0.23–0.42) and donation after cardiac death (OR 0.26, 95%CI 0.22–0.31) compared with if a collaborative approach was employed. Other modifiable factors that significantly improved consent rates included less than six relatives present during the formal approach; the time from intensive care unit admission to the approach (less for donation after brain death, more for donation after cardiac death); family not witnessing neurological death tests; and the relationship of the primary consenter to the patient. These modifiable factors should be taken into consideration when planning the best bespoke approach to an individual family to discuss the option of organ donation as an end-of-life care choice for the patient.  相似文献   
40.
The role of ex vivo normothermic perfusion (EVNP) in both organ viability assessment and reconditioning is increasingly being demonstrated. We report the use of this emerging technology to facilitate the transplantation of a pair of donor kidneys with severe acute kidney injury (AKI) secondary to rhabdomyolysis. Donor creatinine was 10.18 mg/dl with protein (30 mg/dl) present in urinalysis. Both kidneys were declined by all other transplantation units and subsequently accepted by our unit. The first kidney was perfused with red cell-based perfusate at 37°C for 75 min, mean renal blood flow was 110 ml/min/100 g and produced 85 ml of urine. Having demonstrated favorable macroscopic appearance and urine output, the kidney was transplanted into a 61-year-old peritoneal dialysis dependent without complication. Given the reassuring information from the first kidney provided by EVNP, the second kidney was not perfused with EVNP and was directly implanted to a 64-year-old patient. The first kidney achieved primary function and the second functioned well after delayed graft function. Recipient eGFR have stabilized at 88.5 and 55.3, respectively (ml/min/1.73 m2), at 2 months posttransplant.  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