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   935篇
  免费   106篇
  1041篇
  2017年   10篇
  2015年   22篇
  2014年   16篇
  2013年   23篇
  2012年   35篇
  2011年   27篇
  2010年   15篇
  2009年   21篇
  2008年   17篇
  2007年   23篇
  2006年   23篇
  2005年   14篇
  2004年   14篇
  2003年   25篇
  2002年   30篇
  2001年   36篇
  2000年   42篇
  1999年   24篇
  1998年   9篇
  1997年   9篇
  1995年   13篇
  1994年   7篇
  1993年   13篇
  1992年   16篇
  1991年   15篇
  1990年   26篇
  1989年   19篇
  1988年   21篇
  1987年   13篇
  1986年   12篇
  1985年   25篇
  1984年   26篇
  1983年   10篇
  1982年   15篇
  1981年   25篇
  1980年   29篇
  1979年   15篇
  1978年   40篇
  1977年   21篇
  1976年   28篇
  1975年   24篇
  1974年   28篇
  1973年   20篇
  1972年   9篇
  1971年   8篇
  1969年   10篇
  1968年   12篇
  1967年   7篇
  1966年   7篇
  1950年   7篇
排序方式: 共有1041条查询结果,搜索用时 15 毫秒
991.
992.
Two cases of soft-tissue infection resulting from antibiotic therapy given AIDS patients are presented. Operative treatment resulted in a closed wound in one patient. In the other patient, who suffered from recurrent acute illnesses, nonoperative treatment resulted in slow wound contraction and epithelialization without secondary wound complications. Wound sepsis did not occur, despite the absence of normal immune function. Operation and additional hospitalization, with their attendant risks, were avoided.  相似文献   
993.
Spiroelliptin, a spiro[cyclohexadienone-1,1′-tetralin] from Iryanthera elliptica, was synthesized by a novel process which involved the catalytic hydrogenation of the appropriate chalcone. This and other spiro[methoxycyclobexadienone-1,1′-tetralin] derivatives, obtained by the same process or by the oxidative coupling of the appropriate 1,3-diarylpropanes, were used as models in the compilation of 1H and 13C NMR data allowing the recognition of three such naturally occurring structural types.  相似文献   
994.
Steroids with nonpolar side chains with 2, 4 and 8 C atoms were used as substrates for the 11 alpha-hydroxylase of Rhizopus nigricans. Their bioconversion was compared to that of progesterone, which was found to be far the best substrate giving the highest total bioconversion. 3-keto-4-ene steroids with nonpolar side chains were converted to their hydroxylated products in a small yield or not at all. The absence of an oxygen function in the side chain did not affect the regio-specificity of the hydroxylation, but resulted in a much lower total bioconversion. The strong effect of the oxygen function and of the length of the side chain on hydroxylation with the 11 alpha-hydroxylase of Rhizopus nigricans was demonstrated.  相似文献   
995.
996.
Cyanogenesis of 800 plant specimens (108 species) growing on a sandy tract of land between the sea and an inner lagoon 400 m distant was found to increase with insect density and, hence, with distance from the seashore and seasonal variation towards summer.  相似文献   
997.
Summary Results of immunotherapy with BCG in patients with malignant melanoma, breast cancer, and acute leukemia are described. The first study demonstrated that high doses of living BCG organisms (6×108 viable units) delivered by scarification in the upper arms and legs prolonged the disease-free interval and survival of 52 malignant melanoma patients with regional lymph node metastases compared to 218 comparable surgical control patients. Patients with trunk and extremity, but not head and neck melanoma, benefited from BCG, suggesting the importance of the delivery of BCG into the tumor-involved lymphatics.The second study evaluated the therapeutic efficacy of living BCG organisms by scarification in a group of adult acute leukemia patients after the cessation of chemotherapy. Thirty-seven patients had been in remission on intermittent chemotherapy for 12–24 months. Following late intensive consolidation chemotherapy, 7 consecutive patients received no further therapy and then 30 consecutive patients received BCG. Patients maintained on BCG have had a prolonged disease-free interval compared to those given on no further therapy (P=0.07) or compared to a group of similar patients maintained on chemotherapy alone (P=0.001). Similarly, the survival has been improved for patients maintained on BCG compared to those left unmaintained (P=0.009), or those maintained on chemotherapy (P=0.001).The principles of intermittent chemotherapy combined with BCG immunotherapy, first developed in patients with disseminated melanoma and acute myelogenous leukemia, have been confirmed in a series of patients with disseminated breast cancer. Forty-five patients treated with a combination of 5-FU, adriamycin, and cyclophosphamide (FAC) plus BCG by scarification showed prolongation of remission as well as survival compared to a comparable group of 44 patients treated with FAC chemotherapy without immunotherapy. Thus, 23/44 patients treated with FAC have died (median=14 months) compared to only 5/45 patients on FAC-BCG (median=12+ months), P=0.005. The limitations of BCG immunotherapy as well as speculations for future developments of immunotherapy are discussed.This work was supported by Contract No1-CB 33888 from the National Institutes of Health, Public Health Service, Bethesda, Maryland 20014. Drs. Gutterman and Mavligit are the recipients of Career Development Awards (Ca 71007-02 and CA 00130-01, respectively) from the National Institutes of Health, Education, and Welfare, Bethesda, Maryland 20014.  相似文献   
998.
999.
Aniba rosaeodora wood was shown to contain (—)-rubranine. An optically inactive form of this citrylidene-chalcone was previously considered to be an artifact of extraction. The constitution of rubranine was confirmed by pyrolysis and syntheses, involving previously reported pyridine-catalysed condensation of pinocembrin and citral, whereby novel intermediates were prepared, and the acid-catalysed condensation of pinocembrin with geraniol followed by oxidation.  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