全文获取类型
收费全文 | 6751篇 |
免费 | 327篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 181篇 |
儿科学 | 543篇 |
妇产科学 | 246篇 |
基础医学 | 702篇 |
口腔科学 | 120篇 |
临床医学 | 387篇 |
内科学 | 1173篇 |
皮肤病学 | 383篇 |
神经病学 | 455篇 |
特种医学 | 139篇 |
外科学 | 1204篇 |
综合类 | 104篇 |
一般理论 | 1篇 |
预防医学 | 344篇 |
眼科学 | 177篇 |
药学 | 463篇 |
中国医学 | 36篇 |
肿瘤学 | 440篇 |
出版年
2023年 | 35篇 |
2022年 | 98篇 |
2021年 | 188篇 |
2020年 | 113篇 |
2019年 | 121篇 |
2018年 | 156篇 |
2017年 | 127篇 |
2016年 | 160篇 |
2015年 | 197篇 |
2014年 | 282篇 |
2013年 | 330篇 |
2012年 | 455篇 |
2011年 | 504篇 |
2010年 | 325篇 |
2009年 | 235篇 |
2008年 | 425篇 |
2007年 | 384篇 |
2006年 | 392篇 |
2005年 | 373篇 |
2004年 | 320篇 |
2003年 | 282篇 |
2002年 | 302篇 |
2001年 | 85篇 |
2000年 | 75篇 |
1999年 | 80篇 |
1998年 | 70篇 |
1997年 | 47篇 |
1996年 | 39篇 |
1995年 | 53篇 |
1994年 | 42篇 |
1993年 | 37篇 |
1992年 | 39篇 |
1991年 | 62篇 |
1990年 | 72篇 |
1989年 | 65篇 |
1988年 | 64篇 |
1987年 | 59篇 |
1986年 | 43篇 |
1985年 | 57篇 |
1984年 | 45篇 |
1983年 | 23篇 |
1982年 | 20篇 |
1981年 | 25篇 |
1980年 | 17篇 |
1979年 | 28篇 |
1978年 | 18篇 |
1976年 | 15篇 |
1974年 | 12篇 |
1973年 | 16篇 |
1970年 | 12篇 |
排序方式: 共有7098条查询结果,搜索用时 15 毫秒
31.
32.
Purpose
We determined if separation of spermatozoa (washed) on a discontinuous colloidal suspension of silica (Percoll†) density gradient before cryopreservation improves post-thaw motility compared to an unprocessed (raw) cryopreserved sample.Materials and Methods
Ten normal healthy volunteers recruited into the andrology laboratory donor program were studied. Raw and washed cryopreserved spermatozoa were compared for loss of motility with time, motion characteristics, viability and membrane integrity after incubation for 1, 6 and 24 hours. Within group comparisons were made to baseline measurements (0 hours before incubation).Results
Raw and washed cryopreserved spermatozoa showed statistically significant decreases in motility and other motion characteristics after thawing. There were significant decreases in motility and other motion characteristics after incubation periods of 1, 6 and 24 hours, and significant decreases in viability and membrane integrity at 6 and 24 hours in the unprocessed spermatozoa. Although, motility and motion characteristics of washed samples decreased significantly with longer incubation periods, loss of motility with time (longevity) was greater in raw samples. Washed samples retained greater sperm motility for up to 24 hours (p less than 0.03).Conclusions
Specimens prepared by Percoll separation techniques before freezing offer the possibility of selecting spermatozoa that retain motility for up to 24 hours. This finding can be of benefit for couples undergoing intrauterine insemination to achieve pregnancy. 相似文献33.
Ashok N. Kukadia Cesar J. Ercole Paul Gleich Hugh Hensleigh Jon L. Pryor 《The Journal of urology》1996,156(5):1643-1646
Purpose
The long-term effects of testicular trauma on reproductive function are unknown. In an effort to define the relationship between testicular injury and fertility in humans, we identified patients with a history of testicular trauma and assessed parameters commonly associated with fertility.Materials and Methods
We reviewed 15 patients 23 to 59 years old who underwent immediate exploration after testicular trauma between 1972 and 1991. Of the patients 11 were contacted and 8 returned for prospective followup. Reproductive and sexual histories, physical examination, measurements of serum hormones and antisperm antibodies, semen analysis and scrotal ultrasound were done.Results
Of the 8 patients 1 (13 percent) achieved and 7 (87 percent) did not attempt conception. Hormonal status was normal in all 8 patients. Six men had objective evidence of subfertility by semen analysis only, although none had severe oligospermia or asthenospermia and only 1 had severe teratospermia. Five of 9 traumatized testes were atrophic. Interestingly, only 1 patient had antisperm antibodies, the levels of which were probably low enough to be clinically insignificant.Conclusions
There was definite evidence of subfertility as assessed by abnormal semen analyses and atrophic testes following testicular trauma. However, the subfertility did not appear to be immune mediated nor did the patients present with infertility. Since only 1 patient had severely compromised fertility according to semen analysis we conclude that early repair can help preserve hormonal function as well as fertility. 相似文献34.
Sachar RK Singh WP Verma J Gill PJ Sehgal R Singh H Soni RK 《Indian journal of maternal and child health : official publication of Indian Maternal and Child Health Association,》1991,2(3):79-81
In India, interviews were conducted with 250 couples who had at least 2 living children and at least 1 son so researchers could examine the effect of child loss on contraceptive usage. The interviewees lived in the area served by the rural health center in Pohir. 67 couples had lost a child. The child loss group had an acceptance rate for contraception of 41.7% compared to 44.8% for the group who had not experienced child loss. The difference was insignificant. Caste, literacy, and parity did not affect contraceptive usage. These findings suggest that child loss does not play a crucial role in contraception acceptance. On the other hand, some studies show that it is a barrier to fertility limitation. Additional studies are needed to resolve the issue of child loss and fertility. 相似文献
35.
36.
Compromised kidney graft rejection response in Vervet monkeys after withdrawal of immunosuppressants tacrolimus and sirolimus 总被引:2,自引:0,他引:2
Chen H Peng J Luo H Loubeau M Wan X Xu D Qi S Vu MD Daloze P Fitzsimmons WE Bekersky I Peets J Sehgal SN Wu J 《Transplantation》2000,69(8):1555-1561
BACKGROUND: In nonprimates, organ allografts are often not rejected after withdrawal of immunosuppression. In this study, we examined whether such a phenomenon also occurs in primates. METHODS: Vervet monkeys were transplanted with renal allografts and treated for 60 days with tacrolimus, or tacrolimus plus sirolimus. The drugs were totally withdrawn on day 61. The survival of the monkeys was monitored, and their response to donor- or third party-derived alloantigens was examined in vivo and in vitro. RESULTS: The majority (80-100%) of the grafts survived for at least additional 30 days with no signs of acute rejection. The compromised rejection is donor-specific, because recipient monkeys failed to reject a donor-derived skin graft, but a third-party skin graft was rejected. In vitro mixed lymphocyte reaction and interleukin-2 production in the mixed lymphocyte reaction between the recipients and their donors or between the recipients and a third party had no discernable patterns, and thus did not reflect the in vivo status of the immune system. Although the recipients could not reject the graft acutely after drug withdrawal, the kidney grafts and the donor-derived skin grafts had pathological findings of chronic rejection. CONCLUSIONS: The rejection response of the monkeys to an established graft after withdrawal of immunosuppression is compromised. The compromised rejection is specific and is not due to a permanent alteration of the immune system by the initial drug treatment. The allografts are not inert but have low levels of interaction with the recipient immune system. 相似文献
37.
Ashok C Illapakurthy Christy M Wyandt Steven P Stodghill 《European journal of pharmaceutics and biopharmaceutics》2005,59(2):325-332
A novel isothermal titration calorimetry method was used to determine the complexation thermodynamics for hydroxypropyl-beta-cyclodextrin with artemisinin and naproxen at varying temperature and pH. The new method is very useful for studying complexation reactions between cyclodextrin and drugs with poor solubility and all the thermodynamic parameters of the cyclodextrin complexation were determined. The analysis of the thermodynamic data reveals involvement of hydrophobic bonding in the cyclodextrin complexes studied. The data also reveals the presence of enthalpy-entropy compensation in the system and provide information as to the orientation of the drug molecule inside the cyclodextrin cavity. From the thermodynamic parameters for dissociation of HPBCD complexes of artemisinin and naproxen at pH 2 it is concluded that the complexation is primarily driven by enthalpy with entropic assistance at all temperatures studied. From the dissociation studies of HPBCD complexes of naproxen at pH 10 it is concluded that the complexation is predominantly driven by entropy and moderately by enthalpy at lower temperatures and by enthalpy with entropic assistance at higher temperatures. 相似文献
38.
Jaimanti Naresh K. Panda Suresh Sharma Ashok K. Gupta S. B. S. Mann 《Indian journal of otolaryngology and head and neck surgery》2004,56(2):99-104
Conclusion Patients with stage I and II tumors had the best results with radical radiotherapy alone 5 years survival for patients with
stage I and stage II tumors was 90-95% and 75-85% respectively Patients with advanced stage III & IV disease were treated
Unoperable stage IV cancer patients had poor outcome and received only palliative treatment 相似文献
39.
P W Ashok H Hamoda G M M Flett A Templeton 《International journal of gynaecology and obstetrics》2004,87(2):188-193
OBJECTIVE: To compare side effects, women's acceptance and satisfaction with mifepristone (100 mg) versus the Yuzpe regimen for emergency contraception (EC). METHODS: A total of 1000 women requesting EC within 72 h of unprotected intercourse were randomized to receive mifepristone 100 mg or the standard Yuzpe regimen. Outcome measures included patient acceptability and satisfaction. RESULTS: A total of 620 (62%) questionnaires were returned, 64% in the mifepristone group and 60% in the Yuzpe group. Mifepristone was better tolerated than the Yuzpe regimen. The rates of nausea (P<0.0001), abdominal pain (P=0.001), tiredness (P<0.0001), lethargy (P=0.001), hot flushes (P<0.0001) and dizziness (P<0.0001) were all significantly higher in women given the Yuzpe regimen compared to those who received mifepristone. Of these 94% and 80% in the mifepristone and Yuzpe groups, respectively, were satisfied with treatment (P<0.0001). Of women in the mifepristone group, 56% (181/321) had used the Yuzpe regimen of EC in the past and of these, 93.6% (161/172) indicated they would use mifepristone in the future. A total of four women in the Yuzpe group had mifepristone in the past and all four said they would use mifepristone in the future. CONCLUSION: Mifepristone has high patient acceptability and few side effects compared to the standard Yuzpe regimen for EC. 相似文献
40.
Michael D Benson Hiroshi Kobayashi Lakshman R Sehgal Hidekazu Oi Elaine I Haney 《The journal of maternal-fetal & neonatal medicine》2006,19(1):31-34
OBJECTIVES: To assess the relationship, if any, between complement, fetal antigen, and shaking rigors during labor and delivery. METHODS: We recruited 13 volunteers for serial blood sampling during labor and childbirth. RESULTS: Complement levels had a small but significant drop (11-15%) immediately following childbirth but had no association with fetal antigen levels or shaking rigors. Fetal antigen levels failed to show any consistent relationship with shaking rigors or the labor and delivery process. CONCLUSION: Shaking rigors do not appear to be associated with changes in either complement or fetal antigen levels. Complement levels remain stable during labor but drop immediately following birth. 相似文献