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   149100篇
  免费   33856篇
  国内免费   1241篇
耳鼻咽喉   3022篇
儿科学   3955篇
妇产科学   3290篇
基础医学   9286篇
口腔科学   5928篇
临床医学   30901篇
内科学   35022篇
皮肤病学   3889篇
神经病学   17106篇
特种医学   5395篇
外国民族医学   4篇
外科学   26751篇
综合类   919篇
现状与发展   40篇
一般理论   70篇
预防医学   17920篇
眼科学   3604篇
药学   4360篇
中国医学   67篇
肿瘤学   12668篇
  2024年   555篇
  2023年   5170篇
  2022年   1384篇
  2021年   3573篇
  2020年   5740篇
  2019年   2808篇
  2018年   7847篇
  2017年   7975篇
  2016年   8618篇
  2015年   8810篇
  2014年   11821篇
  2013年   14159篇
  2012年   6934篇
  2011年   6975篇
  2010年   8721篇
  2009年   10843篇
  2008年   6629篇
  2007年   5740篇
  2006年   6908篇
  2005年   5565篇
  2004年   4913篇
  2003年   4289篇
  2002年   4160篇
  2001年   2265篇
  2000年   1473篇
  1999年   2207篇
  1998年   2776篇
  1997年   2505篇
  1996年   2494篇
  1995年   2202篇
  1994年   1562篇
  1993年   1341篇
  1992年   1094篇
  1991年   992篇
  1990年   806篇
  1989年   814篇
  1988年   776篇
  1987年   643篇
  1986年   600篇
  1985年   592篇
  1984年   718篇
  1983年   694篇
  1982年   748篇
  1981年   705篇
  1980年   619篇
  1979年   309篇
  1978年   412篇
  1977年   407篇
  1976年   312篇
  1974年   307篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
BACKGROUND: The results from four phase III, randomized, vehicle-controlled studies showed that imiquimod 5% cream (imiquimod) was safe and effective in the treatment of actinic keratosis (AK). Patients applied imiquimod or vehicle cream to AK lesions on the face or balding scalp, dosing three times per week or two times per week for 16 weeks. OBJECTIVE: To obtain long-term safety follow-up data and estimate AK recurrence in patients who completely cleared their AK lesions in the treatment area at the 8-week post-treatment visit in the phase III studies. METHODS: One hundred forty-six patients from 30 study centers in the United States were evaluated for clinical evidence of AK, and safety data were collected. RESULTS: After a median follow-up period of 16 months, 24.7% (19 of 77) of the patients administered imiquimod three times per week and 42.6% (23 of 54) of the patients administered imiquimod two times per week had a recurrence of AK (the appearance of at least one AK lesion) in the original treatment area. The median number of AK lesions present was one lesion for both patients receiving imiquimod three times and those receiving imiquimod two times per week compared with a median of six lesions at baseline in the combined three times per week and two times per week phase III studies. There were no long-term safety issues, and the skin quality seen in the imiquimod-treated patients at the end of the phase III studies was maintained. CONCLUSION: One and a half years following treatment, imiquimod continued to provide a long-term clinical benefit in a majority of patients who experienced complete clearance of their AK lesions.  相似文献   
992.
993.
Early to mid-term fetuses heal cutaneous incisional wounds without scars; however, fetal response to burn injury has not been ascertained. We present a fetal model of thermal injury and subsequent analysis of fetal and lamb response to burn injury. A reproducible deep dermal burn injury was created in the fetus by application of water at 66 degrees C for 7 seconds, and at 82 degrees C for 10 seconds to the lamb. Macroscopically, the area of fetal scald was undetectable from day 7 post injury, while all lamb scalds were readily identified and eventually healed with scarring. Using a five-point histopathology scoring system for alteration in tissue morphology, differences were detected between control and scalded skin at all stages in lamb postburn, but no difference was detected in the fetal model after day 7. There were also large differences in content of alpha-smooth muscle actin and transforming growth factor-beta1 between control and scalded lamb and these differences were statistically significant at day 14 (P < 0.01). This novel model of fetal and lamb response to deep dermal injury indicates that the fetus heals a deep burn injury in a scarless fashion. Further elucidation of this specific fetal process of burn injury repair may lead to improved outcome for patients with burn injury.  相似文献   
994.
995.
996.
Background Results from in vitro and animal studies suggest that cyclooxygenase (COX) inhibitors may reduce the risk of melanoma, but among humans, the evidence remains limited.
Objective In a pilot retrospective cohort, to determine the relationship between the use of COX inhibitors and the incidence, recurrence, and metastases of melanoma in high-risk patients.
Methods Reviewing computerized records at the Miami Veterans Affairs Medical Center, we retrospectively examined the association between COX inhibitor use and melanoma incidence, recurrence, and metastases in high-risk subjects: white subjects previously diagnosed with melanoma (1996–2003). We evaluated three potential outcomes: new melanoma diagnosis, recurrence of a previous melanoma, and melanoma metastasis.
Results Eighty-three subjects with melanoma were included. There was one metastasis among 28 subjects prescribed COX inhibitors, whereas four new melanomas (7.3%), two melanoma recurrences, and six metastases (10.9%) occurred among 55 patients not prescribed COX inhibitors. Although no individual outcomes measures reached statistical significance, combining the three measures, these were significantly lower in users of COX inhibitors compared with nonusers (1 vs 12;  p = .05  ). After adjustment for age and tumor depth of invasion, COX inhibitor users had significantly lower rates of melanoma outcome measures (odds ratio 0.08; 95% confidence interval 0.01–0.77;  p = .03  ).
Conclusion Potential exists for chemoprevention of melanoma among high-risk patients.  相似文献   
997.
Humoral hypercalcemia of malignancy is widely associated with tumor production of parathyroid hormone related protein (PTH-rP). This peptide functions in endocrine, autocrine and paracrine mechanisms in a manner similar to PTH; increasing renal uptake of calcium, decreasing retention of phosphorous, and stimulating adenylate cyclase and phospholipase C. Although PTH-rP production has been well documented in neoplasms of the exocrine pancreas, we present here two cases of endocrine pancreatic neoplasms elaborating PTH-rP. We then review the literature of previous cases and delve into the pathophysiology of this peptide.  相似文献   
998.
999.
1000.
BACKGROUND: Patients with varicose veins seek medical assistance for many reasons, including esthetic ones. The development of suitable and more flexible instruments, along with less invasive techniques, enables the establishment of new therapeutic procedures. OBJECTIVE: To compare endovenous great saphenous vein photocoagulation with an 810 nm diode laser and the conventional stripping operation in the same patient. METHODS: Twenty patients selected for operative treatment of primary great saphenous vein insufficiency on duplex scanning were assigned to a bilateral random comparison. In all cases, both techniques were performed, one on each lower limb. Clinically, evaluation was assessed on the seventh, thirtieth, and sixtieth postoperative days. Patients underwent examination with duplex ultrasonography and air plethysmography during the follow-up. RESULTS: Patients who received endovenous photocoagulation presented with the same pain but fewer swellings and less bruising than the stripping side. Most patients indicated that the limb operated on by laser received more benefits than the other. There was only one recanalization and no adverse effects. The venous filling time showed better hemodynamics in both techniques. CONCLUSION: The endovenous great saphenous vein photocoagulation is safe and well tolerated and presents results comparable to those of conventional stripping.  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