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991.
Bernhard J. Eikmanns Max T. Follettie Martin U. Griot Anthony J. Sinskey 《Molecular & general genetics : MGG》1989,218(2):330-339
Summary The ppc gene of Corynebacterium glutamicum encoding phosphoenolpyruvate (PEP) carboxylase was isolated by complementation of a ppc mutant of Escherichia coli using a cosmid gene bank of chromosomal c. glutamicum DNA. By subsequent subcloning into the plasmid pUC8 and deletion analysis, the ppc gene could be located on a 3.3 kb SalI fragment. This fragment was able to complement the E. coli ppc mutant and conferred PEP carboxylase activity to the mutant. The complete nucleotide sequence of the ppc gene including 5 and 3 flanking regions has been determined and the primary structure of PEP carboxylase was deduced. The sequence predicts a 919 residue protein product (molecular weight of 103154) which shows 34% similarity with the respective E. coli enzyme.
Present address: Institut für Biotechnologie 1 der Kernforschungsanlage, Postfach 1913, D-5170 Jülich, Federal Republic of Germany 相似文献
992.
Günther Muth Bernhard Nußbaumer Wolfgang Wohlleben Alfred Pühler 《Molecular & general genetics : MGG》1989,219(3):341-348
Summary Replication of the Streptomyces ghanaensis plasmid pSG5 was shown to be temperature sensitive. The pSG5 replicon is stably inherited at temperatures below 34° C, but is lost at incubation temperatures above this. A family of cloning vectors was constructed using the pSG5 minimal replicon and different marker genes. The vectors obtained are small in size, have an intermediate copy number, possess a broad host range and are compatible with some other streptomycete vector systems. By increasing the incubation temperature, these vectors can be eliminated from their host cells very efficiently. The suitability of the pSG5 vector family for mutating chromosomal genes by gene disruption was demonstrated: pBN10, a pSG5 derivative containing an internal fragment of the phosphinothricyl-alanyl-alanine (PTT) resistance gene pat, was integrated into the chromosomal pat gene of the PTT-producer Streptomyces viridochromogenes thus inactivating PTT resistance. The integrated pBN10 plasmid was rescued from the chromosome, together with an adjacent fragment carrying DNA of the PTT biosynthetic cluster. 相似文献
993.
Bernhard Henrich Ulrich Schroeder Rainer W. Frank Roland Plapp 《Molecular & general genetics : MGG》1989,215(3):369-373
Summary A cloned DNA fragment, carrying the gene for peptidase D (pepD) of Escherichia coli, was partially sequenced. By purification of peptidase D and sequence determination of an amino-terminal oligopeptide the reading frame of the pepD gene, starting with a GTG initiator codon, was unambiguously identified.An overlap of the established nucleotide sequence with the previously sequenced 5 flanking region of the gpt gene allowed the exact distance between pepD and gpt to be calculated. The two genes are pointing towards each other and are separated by 260 bp. A search for open reading frames (ORFs) and the analysis of possible codon usage in the intercistronic region indicate the absence of an additional gene (lpcA) between pepD and gpt. 相似文献
994.
Microdissection of banded human chromosomes 总被引:9,自引:3,他引:6
Gabriele Senger Hermann-Josef Lüdecke Bernhard Horsthemke Uwe Claussen 《Human genetics》1990,84(6):507-511
Summary Physical dissection of metaphase chromosomes is the most straightforward approach for the isolation of DNA sequences from specific chromosome regions. However, conventional microdissection techniques are too crude and inefficient for analysis of the human genome. Here we describe a technique for the precise dissection of single bands from GTG-banded chromosomes. Cells from normal amniotic fluid cell cultures are harvested by the pipette method. Microdissection is performed on an inverted microscope (magnification 1250 x) with the help of extended siliconized glass needles and an electronically controlled micromanipulator. Enzymatic amplification of the dissected DNA allows the construction of band-specific DNA libraries from as few as 20 dissected chromosome fragments. 相似文献
995.
Bernhard Aicher Jürgen Tautz 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,166(3):345-353
1. | During courtship behavior, males of the fiddler crab, Uca pugilator, drum on the ground with their large chela. The types of waves this produces and some of their properties were investigated using a laser Doppler vibrometer and accelerometers under field and laboratory conditions. |
2. | Rhythmical impact onto the substratum by Uca produces 3 types of surface waves: Rayleigh waves and Love waves which contain most of the energy, and the weaker surface P-waves. |
3. | The group velocity of Love-waves is 50–60 m/s in wet sand. Rayleigh waves travel at 70–80 m/s in wet sand and obout 40 m/s in dry sand. The propagation velocity of surface P-waves is 150–160 m/s in compact wet sand and about 140 m/s in wet sand perforated by crab burrows. The group velocity of Rayleigh and Love waves is not influenced by the presence of crab burrows. |
4. | Fast Fourier transform (FFT) spectra of single beats reveal that the energy maxima of Rayleigh and Love waves lie in the frequency range of 340–370 Hz, i.e., at much higher frequencies than the beat rate of the fiddler crabs, which is usually below 40/s. The optimal frequency is independent of the distance from the signalling male. |
5. | In the optimal frequency range, the specific damping coefficient 10 for Rayleigh waves is very low and amounts to 0.13–0.16 dB/cm in wet sand and 0.23–0.49 dB/cm in dry sand. Substrate vibrations of higher frequencies are more strongly damped. |
6. | Considering the size of a fiddler crab, the physical properties of the Rayleigh and Love waves in the optimal frequency range provide a suitable signal for localizing mechanisms which rely on time or phase differences but not on intensity or spectral differences of propagating substrate vibrations. |
996.
Half-site reactivity 总被引:3,自引:0,他引:3
997.
998.
999.
A novel approach to determine the tetracycline susceptibility of Chlamydia trachomatis directly from specimens without cell culture propagation and adaptation has been explored. Out of a total of 1290 genital specimens from a sexually transmitted disease clinic, 211 (16.4%) were positive for C. trachomatis. A tetracycline concentration of 0.032 g/ml completely inhibited the appearance of inclusions in all of the 211 positive specimens. Of the positive specimens, 120 (56.9%) and 18 (8.5%) respectively showed the presence of 1 to 9 and 100 or more inclusions per microtiter well in antibiotic free medium. Other antibiotics are being tested in the same manner.A part of this paper was presented at the Canadian Public Health Association, STD meeting in Ottawa, Canada, 28–29 October 1985 相似文献
1000.
Isovalerate-oxidizing strictly aneerobic bacteria were isolated from marine sediment and sewage sludge in coculture with Desulfovibrio sp. Cells stained Gram positive and behaved Gram positive also in Gram classification with KOH. Isovalerate degradation depended on interspecies hydrogen transfer to syntrophic hydrogen-oxidizing sulfate reducers or methanogens. Isovalerate was the only substrate utilized and was fermented to 3 mol acetate and 1 mol hydrogen per mol substrate. The degradation pathway was studied by enzyme assays in crude cell extracts, and included acetyl-CoA dependent activation of isovalerate, oxidation to methylcrotonyl-CoA and carboxylation to methylgluta-conyl-CoA which is hydrated and cleaved to acetoacetate and acetyl-CoA. Studies with inhibitors and ionophores suggest that energy conservation with this organism depends on either acetate efflux-driven proton symport or on an ion-gradient driven carboxylation mechanism. 相似文献