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   34784篇
  免费   3126篇
  国内免费   82篇
耳鼻咽喉   541篇
儿科学   1192篇
妇产科学   772篇
基础医学   4096篇
口腔科学   690篇
临床医学   3756篇
内科学   7106篇
皮肤病学   805篇
神经病学   2601篇
特种医学   1346篇
外国民族医学   1篇
外科学   5864篇
综合类   574篇
一般理论   25篇
预防医学   2366篇
眼科学   1058篇
药学   2889篇
中国医学   46篇
肿瘤学   2264篇
  2023年   272篇
  2022年   443篇
  2021年   1128篇
  2020年   588篇
  2019年   990篇
  2018年   1132篇
  2017年   787篇
  2016年   790篇
  2015年   843篇
  2014年   1270篇
  2013年   1571篇
  2012年   2255篇
  2011年   2225篇
  2010年   1166篇
  2009年   1073篇
  2008年   1744篇
  2007年   1741篇
  2006年   1634篇
  2005年   1485篇
  2004年   1379篇
  2003年   1212篇
  2002年   1076篇
  2001年   965篇
  2000年   924篇
  1999年   803篇
  1998年   299篇
  1997年   266篇
  1996年   240篇
  1995年   264篇
  1994年   208篇
  1993年   186篇
  1992年   490篇
  1991年   505篇
  1990年   479篇
  1989年   433篇
  1988年   446篇
  1987年   423篇
  1986年   400篇
  1985年   354篇
  1984年   254篇
  1983年   268篇
  1982年   199篇
  1981年   166篇
  1980年   155篇
  1979年   276篇
  1978年   205篇
  1977年   155篇
  1975年   155篇
  1974年   185篇
  1973年   190篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Herniography has been used for 25 years in the diagnosis of occult herniation but has not gained widespread acceptance in the UK, despite studies confirming its high sensitivity and specificity for occult hernias and an excellent record of safety and patient acceptability. The traditional approach in the UK to suspected occult groin herniation has been surgical exploration. This study examined the use of herniography in a single district general hospital to assess its impact in limiting unnecessary groin explorations and allowing discharge of patients without hernias. The case notes of 90 successive patients referred for herniography by the department of general surgery in a single UK district general hospital over an 18-month period were reviewed. Eighty-seven completed examinations were analysed in which 23 hernias were diagnosed in 20 patients. Thirteen patients have undergone hernia repair with resolution of symptoms. There were no false positive examinations, although two inguinal hernias were incorrectly diagnosed radiologically as femoral hernias; there were two false negative examinations where additional hernias were found at laparoscopic repair. There were no reported complications. Twenty-four patients were discharged directly from the surgical clinic after a negative herniogram. Thirty patients were referred to other specialities. No patient had undergone groin exploration after a negative herniogram. Herniography is a useful tool in assessing obscure groin pain and potential occult herniation. It can reliably rule out the presence of a hernia and avoid the need for surgical exploration. Many patients with a negative herniogram can be reassured and discharged, whilst others may be referred on to other specialities safe in the knowledge that an occult hernia has been excluded.  相似文献   
6.
Acoustic analysis of a reading passage was used to identify the abnormal phonatory events associated with adductor spasmodic dysphonia (ADSD) pre- and postinjection of Botulinum Toxin A (Botox). Thirty-one patients (age 22 to 74 years) diagnosed with ADSD were included for study. All patients were new recipients of Botox, and the examination of their voice occurred before and after their initial injection of Botox. Acoustic events were identified from reading samples of the Rainbow Passage produced by each of the patients. These events were examined from sentences containing primarily voiced sound segments. Dependent variables included the number of phonatory breaks, frequency shifts, and aperiodic segments--all variables previously defined by the investigators. Additionally, calculated variables were made of the percentage of time these events occurred relative to the duration of the cumulative voiced segments. A sex- and age-matched control group (+/-2 years) was included for statistical comparison. Results indicated that those with ADSD produced more aberrant acoustic events than the controls. Aperiodicity was the predominant acoustic event produced during the reading, followed by frequency shifts and phonatory breaks. Within the ADSD group, the number of atypical acoustic events decreased following Botox injection. It is important that the occurrence of specific abnormal acoustic events was sufficient to differentiate the disordered speakers from the controls following as well as preceding initial Botox injection, as indicated by discriminant function analysis. This paper complements our previous work using this acoustic analysis method for defining the abnormal events present in the voice of those with ADSD and further suggests that these measures can be used in conjunction with perceptual impressions to differentiate speakers on the basis of initial severity.  相似文献   
7.
Three cases of enteritis necroticans seen at Port Moresby General Hospital are described. All three cases proved diagnostic problems and in all three the diagnosis was made only at laparotomy. While the condition is uncommon in Port Moresby, these cases indicate that it must now be considered earlier rather than later.  相似文献   
8.
Background: This is the second of two papers using qualitative methods from a study of an intervention for family members affected by close relatives' substance misuse problems.

Participants: 168 primary healthcare professionals (PHCPs: GPs, practice nurses and health visitors) working in general practices in two areas of England, and who took part in the study.

Data sources: Recruitment and post-session forms completed by PHCPs; telephone interviews with each PHCP 12 weeks after recruitment of a family member; interviews with PHCPs at the end of the study.

Results: At the end of the project PHCPs were overwhelmingly positive about the family member intervention and about primary care as the appropriate site. Difficulties were encountered, however, in identifying and engaging affected family members, who were often excluded on grounds of the complexity of their problems or the level of their distress. Shortage of PHCP time and other practice-related factors added to the difficulty. Active work by a PHCP was often necessary in order to make the link between presenting symptoms of physical or mental ill-health and the existence of a family substance misuse problem. When family members were identified and recruited, PHCPs were usually positive about what was achieved. Nearly all were in favour of an approach that combined giving a self-help manual with some follow-up contact with a family member as needed.

Conclusions: Taken in conjunction with statistical outcome findings of significant reductions in symptoms and changes in ways of coping, plus qualitative analysis of the views of family members, the present results encourage the view that a flexible form of this intervention should be developed for use in primary healthcare, and that further work should build on existing strengths and attempt to overcome weaknesses identified.  相似文献   
9.
Encapsulation of proteins in poly(lactide-co-glycolide) microspheres via emulsion is known to cause insoluble protein aggregates. Following protein emulsification and encapsulation in PLGA microspheres, we used circular dichroism to show that the recoverable soluble protein fraction also suffers subtle conformational changes. For a panel of proteins selected on the basis of molecular size and structural class, conformational stability measured by chemical denaturation was not indicative of stability during emulsion-encapsulation. Partial loss of structure was observed for alpha-helical proteins released from freeze-dried microspheres in aqueous buffer, with dramatic loss of structure for a beta-sandwich protein. The addition of sucrose (a lyoprotectant) did not prevent the loss of protein conformation upon encapsulation. Therefore, the conformational changes seen for the released soluble protein fraction originates during emulsification rather than microsphere freeze-drying. Analysis of the burst release for all proteins in buffer containing denaturant or surfactant showed that the degree of protein solubilisation was the dominant factor in determining the initial rate and extent of release. Our data for protein release into increasing concentrations of denaturing buffer suggest that the emulsion-denatured protein fraction remains insoluble; this fraction may represent the protein loss encountered upon comparison of protein encapsulated versus protein released.  相似文献   
10.
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